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VENTILATION,  WEATHER  AND 
THE  COMMON  COLD 

A  Study  of  the  Prevalence  of  Respiratory 

Affections  Among  School  Children  and 

Their  Association  with  School  Ventilation 

and  the  Seasonal  Changes  in  Weather 


BY 

GEORGE  T.  PALMER,  M.S.,  Epidemiologist, 
Detroit  Department  of  Health 


Reprint  from 

THE  JOURNAL  OF  LABORATORY 
AND  CLINICAL  MEDICINE 

St.  Louis 


Vol.  VI,  Nos.  11  and  12,  Vol.  VII,  No.  1,  August, 
September,  and  October,  1921 


VENTILATION,  WEATHER,  AND  THE  COMMON  COLD* 


A   STUDY  OF   THE   PREVALENCE  OF  RESPIRATORY   AFFECTIONS  AMONG   SCHOOL 

CHILDREN  AND  THEIR  ASSOCIATION  WITH  SCHOOL  VENTILATION 

AND  THE  SEASONAL  CHANGES  IN  WEATHER 


BY  GEORGE  T.  PALMER,  M.S.,  EPIDEMIOLOGIST 
DETROIT  DEPARTMENT  OF  HEALTH 


INTRODUCTORY 

DURING  the  last  twenty  years  there  has  been  a  great  amount  of  experimental 
work  on  ventilation  and  its  effect  on  the  body.  Workers  in  Europe  and 
the  United  States  are  in  substantial  agreement  that  it  is  the  thermal  factors — 
temperature,  air  motion  and  humidity — which  exercise  the  greatest  influence 
on  human  comfort,  health  and  efficiency.  The  chemical  composition  of  the 
air  we  ordinarily  breathe — leaving  out  of  consideration  for  the  moment  those 
special  industrial  problems  involving  gases,  fumes  and  dusts — is  of  relatively 
little  moment  in  its  effect  on  human  conduct.  School  children  are  far  better 
off  in  a  cool,  airy  room,  regardless  of  the  carbon  dioxide  content  of  the  air, 
than  they  are  in  air  virgin  pure  chemically  which  is  overheated. 

It  is  most  important  that  the  facts  as  we  have  stated  them  should  be 
clearly  understood,  for  otherwise,  there  is  bound  to  arise,  as  there  has  in 
the  past,  a  misunderstanding  as  to  the  suitability  of  different  methods  of 
ventilating  school  buildings. 

If  variable,  as  opposed  to  uniform,  temperature,  air  motion  and  humidity 
are  desirable  factors,  then  very  satisfactory  conditions  can  be  maintained  in 
school  rooms  by  ventilating  with  the  windows,  protected  by  deflectors,  and 
an  exhaust  duct  on  the  opposite  side  of  the  room,  heating  being  by  direct 
radiation  beneath  the  windows.  This  method  of  ventilating  will  not  always 
give  good  aeration.  At  times  the  room  will  be  amply  flushed  with  outside 
air.  At  other  times,  due  to  shifting  winds,  the  circulation  will  be  lessened, 
the  room  will  not  be  thoroughly  flushed,  and  the  carbon  dioxide  content 
will  rise,  indicating  an  accumulation  of  the  products  of  exhalation  and  body 
vaporization.  Even  though  the  aeration  of  the  room  fluctuates,  it  is  possible 
to  have  coolness  at  all  times  and  variability,  and  if  the  room  is  cool  and 


*This  is  an  abridged  form  of  a  dissertation  presented  in  partial  fulfillment  of  the  requirements  for 
the  degree  of  Doctor  of  Public  Health  at  the  University  of  Michigan,  1920.  > 

This  study  was  conducted  jointly  by  the  Bureau  of  Child  Hygiene  of  the  New  York  City  Depart- 
ment of  Health,  represented  by  Dr.  S.  Josephine  Baker,  Chief  of  the  Bureau,  and  "the  New  York  State 
Commission  on  Ventilation,  represented  by  the  author,  who  then  held  the  position  of  chief  of  the  in- 
vestigating staff.  The  collection  of  sickness  records  and  the  taking  of  temperature  and  other  observations 
on  air  conditions  was  done  by  nurses  and  physicians  of  the  Health  Department  under  the  supervision  of 
Drs.  L.  Marcus  and  R.  H.  Willis.  The  routine  clerical  work  of  tabulation  was  likewise  conducted  by  the 
Health  Department  under  the  immediate  direction  of  Dr.  Franklin  Van  Wart.  The  planning  of  the 
investigation,  selection  of  schools,  initial  instruction  of  the  field  staff  and  the  final  analysis  and  interpreta- 
tion of  results  is  largely  the  work  of  the  author. 

507568 
3 


variable •,wMriii':(>e?taiii.limits.i"t  makes  little  practical  difference  as  to  the 
humidity. 

On  the  other  hand,  if  the  experimental  data  of  the  last  two  decades  are 
wrong  in  minimizing  the  relative  value  of  chemical  purity  of  the  atmosphere, 
then  window  ventilation  as  we  have  described  it  is  inadequate,  and  it  will  be 
necessary  to  insure  at  all  times  voluminous  and  continuous  flushing  of  the 
room  with  outside  air.  This  can  be  done  only  by  mechanical  means,  that  is 
by  plenum  fans  or  blowers. 

There  has  existed  for  some  time  a  controversy  as  to  the  relative  merits  of 
natural  and  mechanical  ventilation.  An  inheritance  from  the  days  of  Pet- 
tenkofer,  when  chemical  purity  was  regarded  as  vital,  has  kept  alive  the 
carbon  dioxide  content  as  the  standard  of  ventilation  goodness.  This 
standard  persists  to  this  day.  Measured  in  these  terms  the  window  venti- 
lated room  falls  into  disrepute.  A  carbon  dioxide  standard  of  6  to  10  parts 
per  10,000  automatically  throws  any  form  of  window  ventilation  into  the  dis- 
card. It  is  only  by  mechanical  means  that  this  degree  of  chemical  purity 
can  be  at  all  times  assured. 

With  the  development  of  mechanical  ventilation  there  has  grown  up  an 
impression  that  uniformity  in  temperature,  in  air  motion  and  in  humidity  is 
ideal,  and  again  the  mechanically  forced  ventilation  far  excells  the  gravity 
method  in  this  respect.  Furthermore  the  dust  in  outside  air  can  be  removed 
readily  under  the  mechanical  system  by  the  introduction  of  air  washers.  This 
is  not  possible  with  window  ventilation. 

There  is  much  then  that  can  be  accomplished  with  the  plenum  system  that 
is  not  possible  under  the  window  method.  The  question  arises  as  to  whether 
the  superiority  of  the  mechanical  system  is  superficial,  a  matter  of  a  relatively 
unimportant  refinement  so  far  as  the  school  classroom  is  concerned.  The 
drawbacks  to  the  mechanically  ventilated  classroom  are  its  tendency  to  over- 
heating, its  unstimulating  uniformity  and  its  greater  expense. 

There  is  much  to  be  said  on  both  sides.  The  advocates  of  window  ventila- 
tion are  impressed  by  its  success  with  tuberculously  inclined  and  undernour- 
ished children.  It  has  a  wide  application  in  our  public  schools  at  the  present 
time.  If  good  for  sick  children,  why  not  for  well  children?  Is  window  ven- 
tilation in  the  schoolroom  to  be  ruled  out  of  consideration  merely  because  it 
fails  to  live  up  to  the  carbon  dioxide  standard?  It  was  for  the  purpose  of 
testing  out  these  principles  on  a  practical  scale  that  the  present  experiment 
was  undertaken.  After  all,  the  proof  of  the  pudding  is  "hi  the  eating.  If 
the  health  of  school  children,  as  measured  by  the  amount  of  respiratory  illness, 
such  as  colds,  tonsillitis,  etc.,  is  better  under  the  more  elaborate  systems 
of  mechanical  ventilation,  then  let  us  proceed  to  equip  our  buildings  in  this 
manner.  If,  on  the  other  hand,  the  mechanical  ventilating  equipment  does  not 
supply  substantial  benefits  to  the  health,  comfort  or  efficiency  of  our  school 
child  population,  or  is  actually  inferior  in  the  things  that  count  for  health,  let 
us  face  the  matter  squarely. 

There  are  innumerable  demands  for  public  funds.  If  we  are  paying  out 
vast  sums  of  money  for  benefits  which  are  not  real  but  imaginary,  recognition 


of  this  fact  cannot  come  too  soon.  If  window  ventilation  provides  the  im- 
portant essentials  of  a  healthy  atmosphere  in  a  way  that  cannot  be  attained 
or  improved  upon  by  mechanical  systems  of  indirect  ventilation,  then  our 
school  buildings  should  be  built  accordingly,  and  we  should  not  hesitate  because 
a  worn  out  standard  of  ventilation  dictates  otherwise. 

During  the  latter  part  of  1916,  from  February  14th  to  April  6th  (8  weeks), 
and  the  winter  of  1916-17,  from  October  30  to  January  26  (12  weeks),  observa- 
tions were  made  on  the  health  of  5500  New  York  City  school  children  who 
were  exposed  to  various  types  of  ventilation  in  12  different  school  buildings. 
In  general  these  ventilation  systems  may  be  classified  under  three  main 
headings,  as  follows: 

A — Cold,  open  window  rooms,  gravity  exhaust. 

B — Cool,   window   ventilated   rooms,    gravity   exhaust. 

C — Plenum,  fan  ventilated  rooms  with  gravity  exhaust  and  with  windows 
closed. 

As  an  index  of  health,  the  sickness  records  of  the  pupils  w^ere  used.  The 
condition  of  the  air  was  determined  by  readings  of  temperature  and  humidity 
and  by  the  personal  sensations  of  the  observers  as  to  temperature,  moisture,  air 
motion  and  odor.  It  would  have  been  desirable  to  determine  also  the  carbon 
dioxide  content  of  the  air,  but  this  involved  analytical  work  which  the  staff 
was  unable  to  do.  The  absence  of  these  latter  data  was  not  serious,  however, 
for  the  Ventilation  Commission  had  available  a  mass  of  data  on  this  subject 
collected  over  two  years'  time,  and  it  was  well  established  that  the  carbon 
dioxide  content  of  fan  ventilated  rooms  averages  several  parts  lower  than  in 
window  ventilated  rooms. 

For  the  convenience  of  the  reader  we  shall  reserve  the  description  of  work- 
ing methods  and  ventilation  types  in  individual  schools  for  the  later  pages 
and  shall  proceed  with  an  account  of  the  findings  of  this  study. 

RESULTS  OF   SICKNESS   SURVEY   IN  DIFFERENT  TYPES  OF  VENTILATED   SCHOOL  ROOMS 

The  first  half  of  the  study  in  the  spring  of  1916  covered  2500  pupils  in 
58  classrooms  distributed  among  8  schools.  The  second  half  in  the  winter  of 
1916-17  was  represented  by  3000  pupils  in  76  classrooms  in  12  schools. 

In  both  studies  the  absences  due  to  respiratory  illness  and  the  respiratory 
illness  among  pupils  present  in  school  was  greatest  in  the  fan  ventilated  rooms, 
Type  C.  This  is  the  result  after  combining  all  records  and  disregarding  in 
this  instance  the  balancing  of  the  type  of  pupil,  location  of  school,  etc.,  which 
will  be  treated  more  at  length  later  on. 

The  excess  of  respiratory  illness  in  the  Type  C  rooms  holds  good  both 
for  absentees  and  those  in  school.  The  total  illness  is  least  in  the  second 
group,  or  cool,  window  ventilated  rooms.  The  difference,  however,  between 
the  first  and  second  types  of  window  ventilation  is  less  than  between  either  the 
first  or  second  and  the  third.  In  other  words,  assuming  for  the  moment  that 
these  differences  are  due  to  atmospheric  influences,  the  air  conditions  in  the 
first  two  types  do  not  produce  greatly  divergent  effects,  but  the  influences  at 
work  in  the  third  type  are  distinctly  less  favorable. 


The  significance  of  these  two  sets  of  results  may  be  expressed  in  this  man- 
ner; for  every  100  cases  of  respiratory  illness  in  the  cool  window  ventilated 
rooms,  there  are  152  in  cold,  window  ventilated  rooms;  and  231  in  fan  venti- 
lated rooms. 


TABLE  I 

RESPIRATORY  ILLNESS  PER  1000  REGISTRATION 
(PUPIL-SESSION)  UNITS* 


Ventilation 
Type 

FIRST   STUDY 

Among           Among 
Absentees-        Pupils 

Total 

SECOND   STUDY 

Among         Among           Total 
Absentees         Pupils 

in  School 

in  School 

A-Cold, 

Window 

Rooms 

10.6 

37.2 

47.8 

9.2 

75.3 

84.5 

B-Cool, 

Window 

Rooms 

10.2 

22.1 

32.3 

10.7 

44.1 

54.8 

C-Fan 

Ventilated 

14.2 

76.0 

90.2 

13.0 

98.4 

111.4 

TABLE  II 
BASIC  FIGURES  FROM  WHICH  RATES  IN  TABLE  I  ARE  COMPUTED 


FIRST   STUDY 


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2,298 

89,067 

822 

6,705 

B 

71,231 

728 

1,578 

113,959 

1,218 

4,661 

0 

65,088 

925 

4,950 

115,215 

1,497 

11,329 

The  actual  temperature  conditions  found  in  the  three  types  of  rooms  are 
disclosed  in  the  two  tables  following,  in  one  of  which  results  are  expressed  as 
averages,  and  in  the  other  by  temperature  groups. 


TABLE  III 
AVERAGE  OF  ROOM  TEMPERATURES 


Ventilation 
Type 


First  Study 


Second  Study 


Mean 


A 

58.8 

59.1 

59.0 

B 

66.9 

65.9 

66.4 

C 

68.8 

67.9 

68.4 

*The  unit  of  illness  was  one  pupil  per  half-day  school  session.  Illness  is  reported  in  pupil  session 
units.  One  pupil  ill  ten  sessions  counted  the  same  as  ten  pupils  ill  one  session.  A  pupil  was  continued 
on  the  register  regardless  of  the  length  of  absence  from  school  unless  it  was  found  that  the  family  had 
moved  away  from  the  school  district,  or  that  the  pupil  had  left  school  permanently. 

Separate  tabulations  have  been  made  of  illness  resulting  in  absence  from  school  and  illness  among 
pupils  who  continued  to  attend  school.  The  absences  are  classified  as  (1)  absence  from  respiratory  illness, 
including  coryza,  bronchitis,  pharyngitis,  laryngitis,  tonsillitis,  pneumonia,  tuberculosis  and  a  miscellaneous 
group  variously  termed  grippe,  colds,  sore  throat,  etc.;  (2)  absence  from  illness  other  than  respiratory, 
namely:  stomachache,  backache,  broken  leg,  etc.  In  this  group  were  also  the  acute  infectious  diseases 
such  as  diphtheria,  measles,  scarlet  fever,  whooping  cough,  chickenpox,  mumps,  etc.  This  was  done  be- 
cause it  was  felt  that  the  spread  of  these  infections  was  largely  determined  by  specific  susceptibility 
rather  than  by  atmospheric  influences;  (3)  absence  due  to  causes  other  than  illness,  such  as  staying 
at  home  to  mind  the  baby,  going  on  a  visit,  shopping  with  parents,  truancy,  etc. 


The  fan  ventilated  or  Type  C  rooms  averaged  but  two  degrees  higher 
than  those  of  Type  B  and  nearly  ten  degrees  warmer  than  Type  A.  Type 
A  was  extremely  cold  for  a  school  room.  Type  B  was  cooler  than  is  cus- 
tomarily found.  The  average  temperature  of  Type  C,  though  higher  than  B, 
was  not  exceptionally  high. 

There  was  a  wide  range  in  the  daily  temperatures,  which  are  lost  sight  of  in 
•the  averages. 

TABLE  IV 

FREQUENCY  DISTRIBUTION  OF  TEMPERATURES 
PER  CENT  OF  SESSIONS 


Types 
Ventilation 

59°  and  below 

60-69°    . 

70°  and  over 

1st  Study 

A 

56 

41 

3 

B 

5 

61 

34 

C 

4 

57 

39 

2nd  Study 

A 

46 

48 

6 

B 

8 

88 

4 

C 

0.2 

99 

0.8 

The  A  rooms  rarely  reached  70°.  Fully  half  of  the  sessions  were  below 
59°.  The  B  and  C  rooms  rarely  fell  below  60°.  The  temperatures  in  the 
second  study  were  much  more  uniform,  particularly  as  regards  Type  C  and  to 
a  lesser  extent  Type  B.  More  than  one-third  of  the  sessions  in  B  and  C  in  the 
first  study  were  above  70°.  Much  of  this  represented  an  overheated  condition. 
However,  the  first  study  was  made  in  the  late  winter,  when  greater  outdoor 
variation  is  experienced  than  from  November  to  January.  Although  the  pro- 
portion of  sessions  between  60  and  70°  does  not  appear  to  differ  much  in  the 
B  and  C  rooms,  yet  there  was  an  appreciable  difference  within  this  range. 
Thus,  in  the  first  study  24  per  cent  of  sessions  in  B  were  from  60°  to  64°, 
whereas  but  6  per  cent  of  the  sessions  in  C  were  within  this  range.  Thirty- 
seven  per  cent  of  B  sessions  were  from  65  to  69  as  against  51  per  cent  of  the 
C  sessions.  The  C  rooms  were  warmer,  as  the  averages  have  already  indicated. 

The  interesting  point  to  be  noted  is  that  whereas  there  was  but  two  de- 
grees difference  in  temperature  between  the  B  and  C  rooms,  there  was  a  wide 
difference  in  the  sickness  rates.  Between  7  and  8  degrees  separated  Types  A 
and  B,  and  yet  in  spite  of  this  the  sickness  rates  were  quite  similar.  Evi- 
dently some  factor  other  than  temperature  operated  differently  on  these  three 
classes  of  rooms  or  else  a  rise  of  two  degrees  above  66°  is  far  more  conducive  to 
colds  than  a  drop  of  as  much  as  7  degrees. 

HUMIDITY 

The  relative  humidity  ranged  from  38  to  46%  and  did  not  differ  greatly  in 
the  three  classes. 

As  would  be  expected,  the  relative  humidity  was  higher  in  the  colder 
rooms.  With  the  same  amount  of  moisture  present  as  in  Type  A,  the  relative 
humidity  in  the  first  study  at  the  temperature  in  Type  B  would  be  33.4, 


V 

RELATIVE  HUMIDITY 


Ventilation                                         First  Study                                         Second  Study 
Type 

A  43,7  46.3 

B  37.8  43.0 

C 37.8 41.2 

and  in  Type  C  31.4.  The  corresponding  figures  in  the  second  study  would 
be  29.9  for  B  and  28.7  for  C.  It  would  appear,  therefore,  that  there  was  an 
accumulation  of  moisture  in  the  Type  B  rooms,  and  this  could  only  come 
from  reduced  aeration.  In  Type  C  the  same  explanation  would  hold.  The 
rooms  at  P.  S.  59  were  humidified,  as  were  also  the  rooms  at  P.  S.  51  and  97, 
but  this  would  hardly  affect  the  average  of  all  rooms  in  the  group  to  this 
extent.  It  is  also  possible  that  the  taking  of  the  humidity  reading  was  not 
as  accurately  done  in  the  dry  rooms,  the  wet  bulb  being  read  before  the  mer- 
cury column  had  completed  its  fall.  These  readings  are  higher  than  we  should 
expect  at  this  season  of  the  year,  judging  from  records  taken  by  the  Com- 
mission in  similar  rooms  in  other  schools. 

Other  indices  of  air  conditions  were  the  opinions  of  the  nurses  who  visited 
the  rooms  at  least  twice  daily. 

FRESHNESS    AND    ODOR 

The  results  of  the  nurses'  votes  on  the  freshness  or  lack  of  freshness  and 
presence  of  odor  in  the  rooms  are  given  in  Table  VI. 

TABLE  VI 


PERCENTAGE    OF    SESSIONS    JUDGED 

Ventilation                               Exceptionally                   Odor  Absent  but 
Type                                            Fresh                         not  Exceptionally 
fresh 

Odorous 

First  Study 
A                                                  62 
B                                                  25 
C                                                  21 
Second  Study 
A                                                  69 
B                                                  18 
C                                                  22 

24 
57 
64 

28 
62 
67 

14 
18 
15 

3.2 
20 
11 

The  results  are  very  interesting  from  several  points  of~view.  The  Type 
B  rooms  are  most  odorous  in  both  studies.  The  excess  over  the  others  was 
slight  in  the  first  study,  18,  as  compared  to  15  for  Type  C  and  14  for  A.  It 
was  more  marked  in  the  second  study,  20,  as  against  11  for  C  and  only  3.2 
for  A. 

The  freshest  rooms  are  the  coldest  rooms.  Sixty-two  per  cent  of  the 
sessions  in  Type  A  in  the  first  study  were  judged  exceptionally  fresh,  and 
in  the  second  study  the  figure  was  69  per  cent.  The  figures  for  Type  B  were 
25  per  cent  in  the  first  and  18  in  the  second.  Type  C  had  21  per  cent  in  the  first 
and  22  per  cent  in  the  second. 

8 


What  seems  clear  from  these  figures  is  that  to  be  exceptionally  fresh  the 
greater  part  of  the  time,  rooms  must  be  well  below  65  degrees  in  temperature. 
Warmer  rooms  may  be  free  from  odor  and  yet  exceptionally  fresh  not  much 
over  one-fifth  of  the  time. 

In  rooms  that  did  not  differ  greatly  in  temperature,  as  B  and  C,  the 
greater  aeration  produced  by  fan  ventilation  reduced  odor  to  a  slight  degree 
in  the  first  study,  and  to  a  marked  degree  in  the  second.  It  failed  to  make 
the  rooms  any  fresher  in  the  first  study,  but  did  help  out  in  the  second  study. 

Although  we  do  not  possess  complete  records  of  the  carbon  dioxide  con- 
tent, there  is  little  doubt  but  that  the  smallest  amount  would  be  found  in  the 
fan  ventilated  rooms,  Type  C,  as  we  have  already  pointed  out.  Repeated 
records  collected  in  three  schools  show  this  tendency  (Table  VII). 

TABLE  VII 
CARBON  DIOXIDE  IN  PARTS  PER  10,000 


SCHOOL 

VENTILATION  TYPE 

B        C 

33 
115 

97 

6.9        5.5 
7.6        6.5' 
8.6        5.7 

The  markedly  greater  freshness  of  the  Type  A  rooms  is  due,  without  ques- 
tion, to  their  low  temperature,  and  not  because  of  the  greater  chemical  purity 
of  the  air.  Freshness  is  not  a  question  of  odor,  for  the  Type  B  rooms  were 
fresher  than  C  and  yet  more  odorous. 


SENSATION  OF   TEMPERATURE 


The  recorded  votes  of  the  nurses  as  to  whether  the  temperature  of  the 
rooms  felt  "too  cool,"  "satisfactory"  or  "too  warm"  are  given  in  Table  VIII. 


TABLE  VIII 


VENTILATION 
TYPE 

PER  CENT  OF  SESSIONS  JUDGED 
TOO  COOL                SATISFACTORY 

TOO  WARM 

First  Study 

A 

7.9 

77 

16 

B 

6.2 

78 

16 

C 

10 

76 

14 

Second  Study 

A 

26 

70 

3.9 

B 

8.6 

80 

11 

C 

3.6 

85 

12 

In  the  first  study  the  per  cent  of  satisfactory  sessions  was  about  the  same 
in  all  three  types,  being  in  the  neighborhood  of  77  per  cent.  There  were  more 
sessions  judged  "too  warm"  in  Types  A  and  B  than  in  C,  although  the  average 
temperature  was  lower  than  C.  The  "too  cool"  sessions  were  most  numerous  in 
Type  C,  the  rooms  of  highest  temperature.  In  other  words,  the  coldest  rooms 
felt  warmer  than  the  warm  rooms.  In  view  of  the  actual  temperature  found,  it 
would  appear  that  the  nurses  were  influenced  in  their  judgment  of  what  the 


temperature  should  have  been  rather  than  by  actual  sensation.  In  no  other 
way  can  we  account  for  the  votes  in  rooms  whose  temperature  differed  by  at  least 
ten  degrees,  as  was  the  case  in  Types  A  and  C. 

The  votes  in  the  second  study  more  nearly  reveal  the  actual  temperature 
condition  as  indicated  by  the  thermometer.  In  A  26  per  cent  of  the  sessions 
were  judged  "too  cool."  In  fact,  4  per  cent  were  voted  "too  cold" — an  ex- 
treme condition.  In  Type  B,  8.6  per  cent  were  "too  cool"  and  in  C  3.6 
per  cent. 

Type  C  had  the  greatest  number  of  sessions  judged  satisfactory  as  to  tem- 
perature; namely,  85  per  cent.  The  corresponding  figure  for  Type  B  was  80 
and  for  A,  70. 

Too  great  warmth  was  experienced  12  per  cent  of  the  time  in  C,  11  per  cent 
in  B  and  but  3.9  per  cent  in  A. 

The  sensation  of  temperature  reflects  the  actual  thermometer  reading — to 
some  extent  at  least.  There  was  much  lesss  overheating  in  the  second  study, 
and  this  agrees  with  the  lesser  number  of  "too  warm"  votes. 

SENSATION  OF   MOISTURE 

As  will  be  seen  from  the  figures  given  below,  over  80  per  cent  of  sessions 
in  all  three  types  of  the  first  study  were  judged  satisfactory  as  to  moisture. 
Both  moisture  and  dryness  were  most  pronounced  in  Type  C. 

TABLE  IX 


VENTILATION 
TYPE 

PER   CENT   OF    SESSIONS    JUDGED 
MOIST                                        SATISFACTORY 

DRY 

First  Study 

A 

5.9 

88 

6.7 

B 

1.7 

89 

9.0 

C 

7.3 

83 

9.7 

Second  Study 

A 

33 

66 

0.6 

B 

20 

74 

6.4 

C 

8.5 

84 

7.9 

The  second  study  reveals  a  greater  divergence  between  the  rooms.  Type 
C  had  the  highest  percentage  of  satisfactory  sessions,  84.  Type  B  had  but  74 
per  cent  and  Type  A,  only  66.  The  cooler  sessions  are  associated  with  moisture, 
the  warmer  sessions  with  dryness. "  One-third  of  all  sessions  in  A  were 
moist  and  less  than  1  per  cent  dry.  Twenty  per  cent  of  sessions  in  B  were 
moist  and  6.4  per  cent  dry.  Eight  and  five-tenths  per  cent  of  C  were  moist 
and  7.9  per  cent  dry. 

There  was  less  overheating  in  the  second  study  and  the  sensation  of 
dryness  is  less.  Type  C  is  similar  in  both  studies.  The  other  two  types  are 
different  in  that  the  second  study  shows  many  more  moist  sessions. 

AIR  MOTION 

The  greatest  proportion  of  satisfactory  votes  as  to  air  motion  was  found  in 
A.  Moving  air  was  noticed  most  frequently  in  A  and  least  in  B.  The  results 

10 


of  both  studies  are  similar,  although  it  is  surprising  to  find  the  sessions  in 
Type  C  judged  "dead"  to  be  more  numerous  in  the  second  study  where  the 
air  flow  through  the  rooms  was  greater  and  the  temperature  was  lower. 


TABLE  X 
PER  CENT  OF  SESSIONS  JUDGED 


VENTILATION 
TYPE 

DEAD                                          SATISFACTORY 

BREEZY 

First  Study 

A 

4.7 

81 

14 

B 

15 

78 

7.1 

C 

9.3 

73 

18 

Second  Study 

A 

9.2 

74 

17 

B 

18 

75 

7.0 

C 

23 

68 

9.8 

ANALYSIS  OF  SICKNESS  RATES  IN  INDIVIDUAL  ROOMS  AND  SCHOOLS 

A  S  we  have  pointed  out  in  the  introductory  remarks,  great  care  must  be 
**•  taken  in  drawing  conclusions  as  to  the  correlation  of  different  facts  from 
the  average  results  of  a  group.  In  the  study  before  us  it  will  be  necessary  to 
inquire  into  the  records  of  each  school  and  of  the  individual  rooms  to  see 
whether  they  agree  uniformly  with  the  characteristics  of  the  group. 

In  Tables  XI  and  XII  are  assembled  records  for  each  room  covering  the 
nature  of  air  conditions  and  the  amotint  of  respiratory  sickness. 

It  is  noticeable  that  there  is  a  wide  variation  in  respiratory  illness.  Room 
415  (Type  B)  at  P.  S.  22  in  the  second  study  had  no  absences  whatever  from 
respiratory  illness.  Room  311  (Type  C),  P.  S.  115,  in  the  second  study,  has  a 
rate  of  50.4.  These  represent  the  minimum  and  maximum  limits.  The  range 
of  respiratory  sickness-in-attendance  rates  is  even  greater — from  zero  to  316. 

Room  311,  P.  S.  59  (Type  A)  is  the  most  congested  in  the  first  study, 
there  being  but  6.5  square  feet  of  floor  space  per  pupil.  In  spite  of  this 
crowded  condition,  the  absence  rate  from  respiratory  disease  is  only  0.6 — one 
of  the  lowest.  On  the  other  hand,  Room  202,  P.  S.  165,  being  the  least  con- 
gested, with  19.6  square  feet  per  pupil,  has  a  respiratory  absence  rate  of  37.0, 
a  very  high  figure.  Overcrowding  does  not  inevitably  lead  to  respiratory 
illness. 

The  average  temperature  of  Type  A  rooms  was  about  59  degrees  in  both 
studies.  This  is  much  colder  than  the  ordinary  school  room.  In  fact,  it 
seems  from  our  general  experience  entirely  too  cold  for  public  school  children, 
and  yet,  on  looking  over  the  absence  rates,  there  is  no  indication  that  these 
children  had  more  colds  as  a  result.  In  fact,  the  average  absence  rate  for  the 
entire  group  is  lower  than  the  other  two  ventilation  types,  as  has  already 
been  pointed  out.  In  the  first  study  there  are  only  two  rooms  in  Type  A  with 
rates  over  20.  There  are  three  each  in  Types  B  and  C.  Respiratory  sickness 
among  those  present  in  school  is  greater  in  Type  A  than  in  B,  but  less  in  A 
than  in  C. 

In  spite  of  the  well  intentioned  efforts  to  balance  the  three  types  of  rooms 
in  the  matter  of  schools  and  type  of  pupil,  this  could  not  be  carried  out  to 

II 


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TABLE  XII 
RECORDS  OF  INDIVIDUAL  ROOMS  IN  SECOND  STUDY 


RESPIRATORY  SICKNESS  RATES 
02           | 

ft* 
1 

AV.  REL. 
HUMIDITY 

PER  CENT 
W 

£        0        H 

5      Q 

PH          O 

W          Q         03 

H         00. 

Type  A  —  Cold  Open  Window 

Eooms 

12 

303 

3.9 

46.6 

50.7 

59.9 

58.0 

28 

0 

2  A 

409 

8.1 

13.7 

21.8 

61.3 

54.4 

18 

0 

4  B 

410 

11.1 

14.2 

25.3 

60.3 

56.0 

33 

0 

4  B 

39 

202 

6.9 

65.0 

71.9 

58.7 

41.3 

65 

4 

3  A 

203 

13 

40.0 

53.0 

56.2 

43.4 

72 

2 

4  A 

204 

21.6 

45.9 

67.5 

56.6 

43.1 

72 

1 

3  B 

205 

6.7 

30.3 

37.0 

58.7 

42.2 

46 

7 

3  B 

206 

9.3 

24.9 

34.2 

58.3 

40.3 

55 

0 

3  A 

207 

11.7 

18.4 

30.1 

57.6 

41.4 

60 

2 

4  B 

59 

308 

4.0 

165 

169 

60.0 

48.0 

100 

0 

3  B 

311 

8.5 

144. 

152.5 

58.5 

48.9 

100 

0 

3  A 

313 

26.8 

213 

239.8 

59.0 

44.7 

85 

11 

2  A 

412 

4.3 

150 

154.3 

58.1 

45.1 

100 

0 

4  A 

413 

9.2 

147 

156.2 

60.0 

48.0 

98 

2 

4  B 

414 

3.0 

124 

127 

57.8 

48.4 

100 

0 

4  A 

416 

8.0 

91.3 

99.3 

57.6 

46.5 

100 

0 

4  B 

73 

301 

5.1 

44.1 

49.2 

60.2 

44.8 

71 

2 

5  B 

309 

11.6 

34.8 

46.4 

58.9 

45.9 

67 

2 

4  A 

402 

6.1 

18.4 

24.5 

60.5 

44.7 

72 

5 

6  A 

403 

6.2 

39.4 

45.6 

63.5 

45.3 

50 

29 

5  B 

Type  B- 

-Moderate 

Temperature,  Open 

Window 

Eooms 

2  Bx. 

301 

10.7 

9.7 

20.4 

68.6 

38.5 

0 

13 

2  B 

302 

7.7 

5.8 

13.5 

69.0 

38.5 

0 

23 

2  B 

316 

11.6 

12.2 

23.8 

65.4 

40.0 

0 

24 

5  A 

12 

405 

9.5 

33.2 

42.7 

62.2 

57.8 

6 

1 

4  A 

408 

15.9 

31.4 

47.3 

63.5 

59.0 

1 

2 

3  B 

12 

411 

9.9 

5.8 

15.7 

63.8 

60.6 

3 

10 

4  A 

22 

415 

0 

0 

0 

67.6 

57.7 

17 

82 

5  B 

416 

5.5 

2.7 

8.2 

68.2 

56.0 

23 

72 

6  A 

418 

.9 

24.6 

25.5 

67.3 

56.7 

29 

65 

5  B 

33  Bx. 

13 

21.4 

55.7 

77.1 

69.3 

31.3 

0 

9 

8  B 

23 

27.5 

47.5 

75.0 

69.4 

37.2 

1 

21 

7  A 

39 

302 

10.9 

33.6 

44.5 

63.0 

40.3 

19 

0 

4  A 

308 

8.6 

42.8 

51.4 

65.0 

37.7 

23 

3 

5  A 

408 

2.9 

58.0 

1  60.9 

65.2 

39.0 

9 

31 

5  A 

59 

318 

3.7 

187 

190.7 

64.9 

48.5 

4 

61 

3  A 

415 

16.2 

158 

174.2 

58.8 

48.2 

100 

0 

4  B 

73 

305 

9.7 

23 

32.7 

61.6 

46.5 

45 

10 

4  B 

406 

2.7 

41 

43.7 

67.1 

43.3 

17 

35 

3  A 

408 

16 

51 

67 

61.1 

43.6 

74  ' 

4 

3  B 

97 

302 

6.4 

37 

43 

67.0 

38.2 

17 

62 

5  B 

313 

7.1 

50 

57 

67.3 

41.8 

71 

17 

4  A 

501 

3.0 

55 

58 

65.9 

44.8 

59 

18 

6  B 

115 

312 

23.3 

— 

— 

67.8 

28.8 

3 

3 

4  B 

502 

40.2 

— 

— 

67.9 

26.2 

2 

3 

5  B 

TABLE  XII  (CONTINUED) 


RESPIRATORY    SICKNESS   RATES 
M 

rn                                      O 

PER  CENT 

H 

SESSIONS 

ri 

^ 

, 

co 

1 

jri 

Is 

III 

a 

PH 
1 

|i 

M 

K 

CQ 

f 

H 

O 

I 

o 
o 

II 

|sE! 

g 

>  ^ 

PH* 
CO 

§ 

cs 

CO 

§ 

<1   H   < 

S 

<! 

•<  w 

H 

0 

0 

503 

29.8 





67.0 

29.5 

0 

3 

5  B 

165 

302 

1.3 

99 

100.3 

67.2 

35.9 

0 

0 

5  B 

306 

10.4 

56 

66.4 

66.8 

35.7 

0 

0 

4  B 

309 

8.1 

33 

41.1 

68.9 

36.1 

0 

0 

4  B 

Type 

C  —  Moderate  Temp. 

,  Fan 

Ventilated, 

Closed 

Window 

Rooms 

2  Bx. 

207 

22.4 

25.5 

47.9 

66.1 

39.6 

0 

13 

2  A 

307 

13.2 

17.0 

30.2 

65.8 

41.2 

0 

35 

O     -D 

310 

1.3 

3.8 

5.1 

66.5 

41.5 

0 

20 

4  B 

22 

402 

4.8 

5.6 

10.4 

66.5 

57.0 

75 

16 

6  A 

403 

3.5 

1.3 

4.8 

65.8 

56.2 

77 

23 

4  B 

22 

404 

14.4 

18 

32.4 

66.5 

54.9 

66 

17 

4  B 

33  Bx. 

14 

29.3 

23 

52.3 

71.0 

28.6 

1 

2 

6  B 

24 

45.4 

125 

170.4 

70.2 

32.0 

3 

3 

5  A 

51  Bx. 

203  (Hum. 

)      4.0 

148 

152 

67.6 

43.6 

0 

39 

6  A 

205 

14.7 

50 

64.7 

67.4 

29.0 

0 

2 

6  A 

59 

203 

16.8 

182 

198.8 

69.2 

47 

10 

12 

6  B 

205 

13.9 

275 

288.9 

69.2 

45.5 

17 

5 

6  B 

206 

9.9 

316 

325.9 

69.6 

46 

16 

1 

6  A 

501 

12.4 

256 

268.4 

68.9 

49 

7 

6 

5  B. 

503 

9.1 

197 

206.1 

69.2 

47.9 

25 

1 

5  B 

505 

8.3 

112 

120.3 

68.7 

49.3 

2 

13 

6  A 

97 

303 

2.3 

34.1 

36.4 

68.0 

43.1 

84 

2 

4  B 

308 

2.7 

34.7 

37.4 

68.3 

40.2 

79 

4 

5  A 

502 

6.8 

43.3 

50.1 

66.3 

44.8 

91 

3 

6  B 

115 

308 

44 

24.8 

68.8 

67 

27.2 

2 

5 

4  A 

311 

50.4 

51.6 

102 

68.2 

25.2 

0 

6 

4  B 

147 

210 

16.6 

11.9 

28.5 

68.1 

42.4 

30 

13 

3  A 

304 

3.6 

6.8 

10.4 

67.7 

40.4 

22 

36 

4  B 

305 

4.2 

12.4 

16.6 

67.1 

42 

49 

9 

5  A 

165 

201 

11.9 

196 

207.9 

68.4 

33.3 

0 

0 

4  A 

202 

5.3 

151 

156.3 

68.0 

34.5 

0 

0 

3  B 

220 

10 

181 

191 

69.2 

35 

0 

0 

4  A 

308 

1.8 

154 

155.8 

68.7 

35 

0 

0 

5  B 

the  degree  desired.  If  the  pupils  in  one  district  are  by  reason  of  hereditary 
and  environmental  influences  more  susceptible  to  colds,  then  this  school  will 
unduly  raise  the  sickness  rate  in  the  ventilation  type  within  which  the  major- 
ity of  its  records  fall. 

Of  the  12  schools  used  in  the  two  studies,  only  one  possessed  all  three 
examples  of  ventilation.  In  one  other  instance  the  three  types  were  repre- 
sented by  two  schools  a  block  or  so  apart,  one  school  having  Type  C  and  the 
other,  Types  A  and  B.  In  all  other  instances  there  were  not  more  than  two 
types  represented  within  a  school  building,  some  buildings  having  A  and  B  and 
others,  B  and  C.  The  division  of  rooms  is  revealed  in  the  table  below. 

One  can  readily  appreciate  by  looking  at  the  table  how  the  results  would  be 
affected  if,  say,  School  39  were  given  to  very  little  sickness  and  School  147  to 


TABLE  XIII 
DISTRIBUTION  OF  TEST  BOOMS  AMONG  THE  TWELVE  SCHOOLS  BY  VENTILATION  TYPE 


FIRST  STUDY 

SECONb  STUDY 

SCHOOL 

A 

B 

C 

A 

B 

C 

12 

3 

3 

0 

3 

3 

0 

147 

0 

0 

3 

0 

0 

3 

22 

0 

3 

3 

0 

3 

3 

59 

5 

3 

6 

7 

2 

6 

73 

4 

3 

0 

4 

3 

0 

165 

0 

3 

4 

0 

3 

4 

39 

6 

3 

0 

6 

3 

0 

2  Bx. 

0 

3 

3 

0 

3 

3 

33  Bx. 

0 

2 

2 

51  Bx. 

0 

0 

2 

97 

0 

3 

3 

115 

0 

3 

2 

Total 

18 

21 

19 

20 

28 

28 

a  great  deal.  In  the  summary  of  all  rooms  Type  A,  having  6  rooms  in  School 
39  would  have  a  low  sickness  rate,  not  because  of  ventilation,  but  because  of 
its  personnel,  and  Type  C  would  be  inclined  to  have  a  high  rate,  not  because 
of  ventilation  but  because  of  the  numbers  of  children  from  School  147.  Theo- 
retically this  influence  should  have  been  eliminated  at  the  beginning,  but 
actually  this  was  found  impossible. 

The   total  respiratory   illness  rate   including  both   absentees   and   those 
present  in  each  school  is  shown  in  Table  XIV. 

TABLE  XIV 
TOTAL  RESPIRATORY  ILLNESS  RATES  BY  SCHOOLS 


SCHOOL 

FIRST  STUDY 

SECOND  STUDY 

97 



46.7 

22 

100.3 

13.6 

12  &  147 

31.1 

27.9 

73 

37.4 

44.2 

51  Bx. 

— 

106.4 

59 

103.1 

193.3 

39 

12.6 

51.6 

2  Bx. 

55.9 

24.2 

165 

77.9 

123.3 

33  Bx. 

— 

92.6 

A  considerable  variation  is  seen  in  the  illness  rates.  Schools  59  and  165 
are  relatively  high  in  both  studies.  Schools  12,  147  and  73  are  low  in  both. 
School  22  is  high  in  the  first  study  and  extremely  low  in  the  second. 

We  may  examine  the  effect  of  ventilation  apart  from  these  extraneous  in- 
fluences mentioned  first  by  inspecting  the  records  of  each  school  by  itself 
and  secondly  by  balancing  the  influence  which  each  school  exerts  on  the  total. 

In  an  effort  to  illustrate  the  comparison  of  illness  rates  within  each  school 
we  have  prepared  Charts  I  and  II,  the  former  showing  Types  A  and  B  and 
the  latter,  B  and  C.  Both  measures  of  illness  among  the  absent  and  among 
those  present  are  included.  The  frequency  with  which  one  ventilation  type 
exceeds  the  other  in  amount  of  illness  conveys  an  impression  that  is  not  brought 
out  in  the  averages  for  each  ventilation  type. 

16 


In  the  comparison  of  the  window  ventilated  rooms  from  the  chart,  Type 
B  exceeds  Type  A  in  respiratory  illness  in  nine  instances.  In  the  remaining 
seven  instances  Type  A  exceeds  Type  B.  There  is  then  no  prevailing  superior- 
ity of  one  type  over  another.  It  will  be  noted  in  the  summary  at  the  bottom 
of  the  chart,  where  the  rates  have  been  averaged,  that  Type  B  shows  less  re- 


COMPARISON  OF  RESPIRATORY   ILLNESS  RATES 
IN  VENTILATION  TYPES  A  (Cold  Open  window  Rooms) 

AND    B     (  Moderate  Temperature,  Open  Window  Rooms) 


Summary 


Chart  I. 

spiratory  illness  than  A.  This  is  due  to  the  influence  of  several  high  rates  in 
Type  A.  Incidentally  this  illustrates  how  an  erroneous  impression  may  be 
gained  from  averages  alone. 

In  the  comparison  between  Types  B  and  C,  the  latter  exceeds  the  former 
in  respiratory  illness  in  eighteen  instances ;  whereas  B  exceeds  C  in  only  seven 


instances.  This  result  is  much  more  significant  than  in  the  previous  comparison. 
The  averages  of  the  rates  are  consistent  with  the  tendency  of  the  individual 
instances.  With  the  new  schools  used  in  the  second  study  included,  the 
average  for  Type  C  exceeds  B  in  both  measures  of  respiratory  illness.  The 
same  is  true  with  the  new  schools  omitted. 


COMPARISON  OF  RESPIRATORY  ILLNESS  RATES 

IN   VENTILATION    TYPES     B     (Moderate  Temperature 
Open  Window  Rooms  )    AND   C     (Moderate  Temperature 
Fair     Ventilated     Rooms) 


SUMMARY 

New  Schools  of  2nd  Studv  Included 


Chart 


This  analysis  confirms  what  has  been  brought  out  previously — that  the 
difference  between  Types  A  and  B  is  insignificant;  whereas,  between  B  and 
C  there  is  a  distinct  excess  of  illness  in  the  fan  ventilated  rooms. 

In  School  59  all  three  types  of  ventilation  are  represented.  We  have  in 
this  instance  a  good  measure  of  ventilation  influences  on  pupils  of  the  same 


18 


general  characteristics.  The  fan  ventilated  rooms  have  the  greatest  respira- 
tory illness  in  both  studies.  The  relative  positions  of  A  and  B  are  not  the  same 
in  the  two  studies,  the  cold  rooms  having  more  illness  in  the  first  study  and  less 
in  the  second. 

TABLE  XV 
RESPIRATORY  ILLNESS  BATES  IN  THREE  VENTILATION  TYPES  AT  SCHOOL  59 


VENTILATION 
TYPE 

FIRST   STUDY 

SECOND   STUDY 

SICKNESS 
CAUSING 

ABSENCE 

SICKNESS 
IN 
SCHOOL 

SUM 

SICKNESS 
CAUSING 
ABSENCE 

SICKNESS 
IN 
SCHOOL 

SUM 

A 
B 

C 

4.6 
9.1 
13.7 

90 

53 
139 

94.6 
62.1 
152.7 

9.0 

10.2 
11.7 

148 

172 

223 

157 
182 
235 

The  room  temperature  for  each  type  -averaged  as  follows: 

A  58.8  58.7 

B  65.4  61.9 

C  68.2  69.1 

The  fan  ventilated  rooms  were  the  warmest,  exceeding  the  Type  B 
rooms  by  2.8  degrees  in  the  first  study  and  by  7.2  degrees  in  the  second. 
These  results  are  consistent  in  showing  less  illness  in  the  window  ventilated 
rooms. 

In  one  other  instance  the  three  ventilation  types  are  to  be  found  divided 
between  two  schools  within  a  block  of  each  other  and  for  all  practical  pur- 
poses the  characteristics  of  the  pupils  are  the  same.  The  sickness  rates  for 
Schools  12  and  147  are  shown  in  Table  XVI. 

TABLE  XVI 
RESPIRATORY  ILLNESS  RATES  IN  THREE  VENTILATION  TYPES  AT  SCHOOLS  12  AND  147 


VENTILATION 
TYPE 

FIRST    STUDY 

SECOND   STUDY 

SICKNESS 
CAUSING 
ABSENCE 

SICKNESS 
TN 
SCHOOL 

SUM 

SICKNESS 
CAUSING 
ABSENCE 

SICKNESS 
IN 
SCHOOL 

SUM 

A 
B 

C 

9.3 
7.0 

6.5 

8.6 

15 
47 

17.9 
22.0 
53.5 

7.7 
-11.7 

8.2 

22 
24 
10 

29.7 
35.7 

18 

(Temperature— 1st  Study  A  60.5,  B  66.6,  C  67.3;  2nd  Study,  A  60.5,  B  63.2,  C  67.6.) 

The  fan  ventilated  rooms  appear  to  better  advantage  in  this  instance, 
for  illness  is  lowest  in  Type  C  in  the  second  study.  In  the  first  study  the  total 
illness  is  greatest  in  the  fan  ventilated  rooms,  although  the  illness  causing 
absence  is  the  lowest  of  the  three  types. 

The  Type  C  rooms  at  School  59  were  unusually  well  equipped  with 
mechanical  ventilation  facilities.  The  air  is  humidified  before  entering  the 
room,  and  the  blowers  are  capably  managed.  The  fan  equipment  at  School 
147  is  older  and  the  rooms  were  not  thoroughly  aerated  at  all  times,  and 
windows  were  frequently  found  open. 

In  view  of  the  oft  repeated  assertion  that  humidification  and  air  washing 
in  combination  with  the  plenum  fan  is  from  many  standpoints  a  superior 

19 


form  of  ventilation,  the  figures  of  this  study  are  of  special  interest.  A 
modern  form  of  mechanical  ventilation  with  warm  temperature  is  associated 
with  more  respiratory  sickness  than  naturally  ventilated  rooms  with  gravity 
exhaust.  On  the  other  hand,  fan  ventilation,  lacking  many  modern  features, 
as  in  P.  S.  147,  is  associated  with  less  respiratory  illness  than  naturally  ven- 
tilated rooms.  At  P.  S.  147  the  temperature  of  the  fan  rooms  was  lower  than 
at  P.  S.  59.  Raising  the  temperature  over  68  degrees  would  seem  to  be  more 
disturbing  to  health  than  reducing  the  volume  of  air  passing  through  the 
rooms. 

The  temperature  of  the  A  rooms  in  all  instances  was  lower  than  those  se- 
lected as  B  rooms.  In  general  the  C  rooms  were  warmer  than  B,  although 
there  were  some  exceptions  to  this. 

TABLE  XVII 

AVERAGE  TEMPERATURE  AND  TOTAL  BESPIRATORY  ILLNESS  RATES  BY 
VENTILATION  TYPES  IN  EACH  SCHOOL 


SCHOOL 

VENTILATION 
TYPE 

FIRST 
TEMP. 

STUDY 
RATE 

SECOND 
TEMP. 

STUDY 
RATE 

12 

147 

A 

B 
C 

60.5 

66.6 
67.3 

17.9 
22.0 
53.5 

60.5 
63.2 
67.6 

29.7 
35.7 
18.2 

39 

A 
B 

57.2 
61.6 

15.5 
9.5 

57.7 
64.4 

50.6 
52.5 

59 

A 
B 
C 

58.8 
65.4 
68.2 

94.6 
62.1 
153 

58.7 
61.9 
69.1 

157 
182 
235 

73 

A 
B 

60.1 
65.3 

58.4 
16.3 

60.8 
66.6 

4]  .2 
47.1 

2  Bx. 

B 
C 

70.4 
69.1 

57.0 
54.8 

67.7 
66.1 

19.6 
28.6 

22 

B 
C 

69.6 
68.1 

51.8 

22.7 

67.7 
66.3 

11.1 
16.1 

165 

B 
C 

69.6 
70.9 

50.4 
105 

67.6 
68.6 

66.0 
180 

33  Bx. 

B 
C 



69.4 
70.6 

76.2 
109 

115 

B 

C 

{  t 

67.6 
67.6 

30.4* 
47.2* 

97 

B 

C 

66.7 
67.6 

52.6 
40.7 

*This 

is  absence  illness  only. 

^ 

Whenever  temperatures  are  over  68  degrees,  the  warmer  rooms  have  the 
greater  sickness,  regardless  of  whether  Type  B  or  C.  When  temperatures 
are  below  68,  the  window  rooms  have  less  sickness  in  four  instances  and 
more  sickness  in  two  instances. 

It  may  be  pointed  out  in  this  connection  that  even  where  the  temperatures 
of  a  fan  and  window  room,  as  measured  at  the  three-foot  level,  are  identical, 
the  window  room  is  actually  cooler,  for  the  temperature  at  the  floor  level  is  al- 
ways lower  in  the  window  rooms. 

2O 


The  second  means  of  shedding  light  on  the  significance  of  the  grand  av- 
erages is  by  equalizing  the  influence  of  each  school  in  each  ventilation  group. 
In  doing  this  we  have  combined  the  two  studies,  omitting  the  schools  that 
were  not  represented  in  both.  Where  there  are  9  rooms  at  a  school,  6  in 
Type  A  and  3  in  Type  B,  we  have  reduced  the  number  in  the  first  type  to  three 
by  averaging  the  two  highest  readings,  the  two  lowest  and  the  two  interme- 
diate. Where  there  are  four  readings,  we  have  averaged  the  two  highest  and 
used  the  other  two  as  they  stand.* 

We  have  illustrated  in  Tables  XVIII  and  XIX  the  manner  of  making 
this  computation  by  showing  the  selected  rates  used  along  with  the  original 
figures. 

In  Table  XX  will  be  found  the  averages  of  the  rates  both  actual  and  ad- 

TABLE  XVIII 

ACTUAL  AND  SELECTED  RESPIRATORY  ILLNESS  RATES  BY  ROOMS 
COMPARISON  OF  TYPES  A  AND  B  (BOTH  STUDIES  COMBINED) 


ABSENCE  RATE 
TYPE  A                TYPE  B 
SCHOOL      ACTUAL   SELECTED    ACTUAL   SELECTED 

ILLNESS  IN  ATTENDANCE  RATE 
TYPE  A             TYPE  B 
ACTUAL   SELECTED   ACTUAL   SELECTED 

12       15. 

15. 

4.5 

4.5 

10. 

10. 

15. 

15. 

8.6 

8.6 

11.3 

11.3 

3. 

3. 

14 

14. 

5.0 

5.0 

5.1 

5.1 

16. 

16. 

17. 

17. 

3.9 

3.9 

9.5 

9.5 

47. 

47. 

33. 

33. 

8.1 

8.1 

15.9 

15.9 

14. 

14. 

31. 

31. 

11.1 

11.1 

9.9 

9.9 

14. 

14. 

6. 

6. 

39       11. 

11. 

6.9 

6.9 

2. 

2. 

0. 

0. 

11. 

21. 

21. 

2. 

14. 

14. 

1.4 

1.4 

2. 

1. 

1. 

1. 

14 

.6 

21 

19. 

0 

0 

0 

0 

17 

0 

6.9 

6.8 

10.9 

10.9 

65. 

55. 

34. 

34. 

6.7 

8.6 

8.6 

46 

9.3 

10.5 

2.9 

2.9 

40 

35. 

43. 

43. 

11.7 

30 

13.0 

17.3 

25. 

21. 

58. 

58. 

21.6 

18. 

59         .6 

.6 

15.1 

15.1 

210. 

151. 

61. 

61. 

.6 

10.9 

10.9 

91 

8.2 

8.4 

1.5 

1.5 

72. 

47. 

91. 

91. 

8.5 

21. 

5.8 

5.8 

74. 

74. 

15. 

15. 

26.8 

3.7 

3.7 

213. 

9.2 

18. 

16.2 

16.2 

165 

189. 

187. 

187. 

8.5 

10. 

124 

8. 

8.3 

91 

108 

158. 

158. 

4.3 

144 

3.0 

3.8 

150. 

147. 

173. 

4. 

147. 

73       25.8 

18.8 

3.2 

3.2 

57. 

57. 

1. 

1. 

11.5 

10.2 

10.2 

34. 

34. 

1. 

1. 

6.4 

6.4 

10.4 

10.4 

32. 

32. 

24. 

24. 

10.8 

10.8 

11.6 

8.9 

9.7 

9.7 

42. 

42. 

23. 

23. 

6.2 

2.7 

2.7 

35. 

35. 

41. 

41. 

6.1 

6.1 

16. 

16. 

18. 

18. 

51. 

51. 

5.1 

5.1 

*This    might    be    done    by    averaging    the    two    lowest    or    the    two    intermediate    rates,    letting    the 
highest  value   stand.     The   difference,    however,   is   too   slight   to   alter   the   final   result. 


TABLE  XIX 

ACTUAL  AND  SELECTED  RESPIRATORY  ILLNESS  RATES  BY  ROOMS 
COMPARISON  OF  TYPES  B  AND  C  (BOTH  STUDIES  COMBINED) 


ABSENCE  RATES                   ILLNESS  IN  ATTENDANCE  RATES 
TYPE  B            TYPE  C             TYPE  B             TYPE  C 
SCHOOL       ACTUAL   SELECTED   ACTUAL   SELECTED   ACTUAL   .SELECTED   ACTUAL   SELECTED 

2  Ex.     3.1 

3.1 

13. 

13. 

36. 

36. 

64. 

64. 

31. 

31. 

.8 

.8 

38. 

38. 

33. 

33. 

16.4 

16.4 

13.3 

13.3 

47. 

47. 

47. 

47. 

10.7 

10.7 

22.4 

22.4 

10. 

10. 

26 

26. 

7.7 

7.7 

13.2 

13.2 

6. 

6. 

17. 

17. 

11.6 

11.6 

1.3 

1.3 

12. 

12. 

4. 

4. 

22        5.7 

5.7 

7.0 

7.0 

7. 

7. 

4. 

4. 

8.5 

8.5 

10.5 

10.5 

7. 

7. 

12 

12. 

8.0 

8.0 

8.9 

8.9 

0 

0 

25. 

25. 

0 

0 

4.8 

4.8 

0 

0 

6. 

6. 

5.5 

5.5 

3.5 

3.5 

3. 

3. 

1. 

1. 

.9 

.9 

14.4 

14.4 

25. 

25. 

18. 

18. 

59       15.1 

15.1 

17.9 

17.4 

61. 

61. 

188. 

176 

10.9 

10.9 

16.9 

91. 

91. 

163. 

1.5 

1.5 

16.8 

14.7 

15. 

15. 

149. 

145. 

12.6 

140. 

10.4 

9.2 

97. 

97. 

8.0 

97. 

3.7 

3.7 

16.8 

15.4 

187. 

187. 

316 

296. 

16.2 

16.2 

13.9 

158. 

158. 

275. 

10. 

12.4 

11.2 

173. 

256. 

227. 

9.9 

197. 

9.1 

8.7 

182 

147. 

8.3 

112. 

12  &      4.5 

4.5 

8.4 

8.4 

15. 

15. 

46. 

46. 

147       11.3 

11.3 

1.5 

1.5 

14. 

14. 

73. 

73. 

5.1 

5.1 

9.6 

9.6 

17. 

17. 

22. 

22. 

9.5 

9.5 

16.6 

16.6 

33. 

33. 

12. 

12. 

15.9 

15.9 

3.6 

3.6 

31. 

31. 

7. 

7. 

9.9 

9.9 

4.2 

4.2 

6. 

6. 

12. 

12. 

165       10.4 

10.4 

37.0 

36.1 

21. 

21. 

156. 

119. 

5.7 

5.7 

35.0 

38. 

38. 

82. 

26.4 

26.4 

34 

34. 

48. 

48. 

34. 

34. 

12. 

12. 

34. 

34. 

1.3 

1.3 

11.9 

11. 

99. 

99. 

196. 

189. 

10.4 

10.4 

10. 

56. 

56. 

181. 

8.1 

8.1 

5.3 

5.3 

33. 

33. 

154. 

154. 

1.8 

1.8 

151. 

151. 

justed.  Where  the  school  influence  is  thus  equalized  in  each  ventilation  type 
the  average  illness  rates  are  appreciably  different  from  the  unconnected  av- 
erages. In  the  comparison  of  Types  A  and  B  only  those  schools  have  been 
used  which  possessed  both  A  and  B  rooms.  A  B  room  in  a  school  not  having 

TABLE  XX 

COMPARATIVE  RATES  OF  RESPIRATORY  ILLNESS  WITH  UNCORRECTED  AND  BALANCED  AVERAGES 

(BOTH  STUDIES  COMBINED) 


VENTILATION 

ABSENCE   RATE 

ILLNESS    IN   ATTENDANCE   RATE 

TYPE 

UNCORRECTED 

BALANCED 

UNCORRECTED 

BALANCED 

A 

10.0 

9.6 

57 

48 

B 

9.0 

9.1 

39 

45 

B 

9.4 

9.4 

38 

43 

C 

12.0 

11.1 

94 

73 

22 


an  A  room  is  omitted.  Similarly,  in  the  comparisons  of  B  and  C  rooms,  B 
rooms  are  omitted  where  there  is  lacking  a  C  room  in  the  same  school. 

Before  correcting  for  number  of  rooms  the  absence  rates  for  A  and  B  were 
10.0  and  9.0.  After  eliminating  the  abnormal  influence  of  the  schools  with 
the  most  rooms,  the  rates  are  9.6  and  9.1.  In  the  first  instance  Type  A  was 
greater  than  B,  largely  because  of  the  greater  number  of  rooms  at  Schools 
39  and  59,  where  the  rates  are  higher. 

The  effect  of  eliminating  the  school  influence  is  even  more  noticeable  with 
the  rates  for  illness  in  attendance.  Without  correction  the  rate  for  A  was 
57  and  for  B,  39,  an  appreciable  difference.  When  the  influence  of  each 
school  has  been  equalized,  the  rates  are  48  for  A  and  45  for  B.  In  the  former 
instance  A  exceeds  B  only  because  it  possessed  more  rooms  at  P.  S.  59,  where 
the  rates  are  high,  and  not  because  of  any  ventilation  influence. 

The  corrected  absence  rates  for  Types  B  and  C  are  9.4  and  11.1,  a  differ- 
ence of  1.7.  Before  the  correction  had  been  applied  the  rates  were  9.4  and  12.0, 
a  difference  of  2.6.  It  was  the  greater  number  of  rooms  at  P.  S.  59,  where 
the  rates  are  high,  that  raised  the  average  for  Type  C.  When  this  influence 
is  modified  the  difference  between  the  two  types  is  less. 

A  marked  alteration  is  also  produced  in  the  rates  for  illness-in-attendance. 
Without  the  correction  for  number  of  rooms,  the  figure  for  B  is  38  and  for  C, 
94,  a  difference  of  56.  Eliminating  the  school  influence  the  rates  are  43 
and  73,  a  difference  of  only  30.  School  59  is  largely  to  blame  for  the  apparent 
wide  difference  in  the  types.  With  an  equal  number  of  rooms  at  each  school 
we  obtain  a  truer  conception  of  the  difference  in  ventilation  types. 

Having  arrived  at  comparative  figures  which  are  believed  to  give  a  fairly 
accurate  measure  of  the  ventilation  influence,  we  are  confronted  with  the 
interpretation  of  these  results.  Is  the  difference  of  0.5  between  the  absence 
rate  in  A  and  B  significant,  or  is  it  a  chance  result  which,  if  the  experiment 
were  repeated,  would  reverse  itself?  We  can  answer  this  question  by  deter- 
mining the  probable  error  of  the  averages.  If  the  differences  are  statisti- 
cally significant,  they  will  represent  at  least  three  times  the  value  of  the  prob- 
able error.  If  the  differences  are  no  greater  than  the  probable  error,  then 
we  cannot  say  that  ventilation  exercises  an  unmistakable  effect  on  the  health 
of  these  school  children. 

The  formula  for  the  probable  error  is 

P.  E.  —  0.6745 


The  computation  of  the  probable  error  is  made  by  averaging  the  absence 
rates  in  each  type:  finding  the  deviation  of  each  rate  from  the  average;  squar- 
ing each  deviation;  averaging  these  squares;  determining  the  square  root  from 
this  average;  dividing  this  figure  by  the  square  root  of  the  number  of  cases, 
which  gives  the  standard  deviation  and  finally  multiplying  this  figure  by  the 
constant,  0.6745,  which  gives  the  probable  error,  or  P.  E. 

The  difference  in  the  absence  rates  between  Types  A  and  B,  0.5,  is  less 
than  the  probable  error,  or  approximately  0.7,  and  in  consequence,  is  without 
significance.  This  means  that  the  evidence  is  insufficient  to  prove  that  either 

23 


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type  of  ventilation  is  superior  to  the  other  in  so  far  as  respiratory  illness  is 
concerned. 

Eespiratory  illness  of  a  less  severe  nature  and  sufficient  to  keep  children 
out  of  school  is  likewise,  judging  by  the  fact  that  the  probable  error  exceeds 
the  difference  in  rates,  no  different  in  a  cold,  window  ventilated  room  with  a 
temperature  around  59  degrees  than  in  a  cool,  window  ventilated  room  whose 
temperature  is  in  the  neighborhood  of  64  degrees.  This  finding  is  in  agree- 
ment with  the  original  computations  for  the  entire  group  of  rooms. 

The  differences  between  Types  B  and  C  are  more  marked.  The  higher 
probable  error  for  absence  rates,  that  is  for  Type  C,  is  1.0.  The  difference 

TABLE  XXI 

PROBABLE  ERROR  OF  RESPIRATORY  SICKNESS  BATES 
(BOTH  STUDIES  COMBINED) 


DIFFERENCE    BETWEEN 

PROBABLE                 DIFFERENCE    BETWEEN                 PROBABLE 

VENTILATION   TYPES 

ERROR 

VENTILATION   TYPES                      ERROR 

A   AND   B 

B   AND   C 

Absence 
Eate 

0.5 

A± 
B± 

.69 
.71 

1.7                           A±    .88 
B  ±  1.00 

Sickness  in 
Attendance 
Eate 

3.0 

A± 

B  ± 

6.9 
7.3 

30                              A  ±  6.1 
B±9.0 

(Note:     Only  schools  used  in  both  studies  are  included  in   the   above.) 

between  the  sickness  rates  is  1.7.  While  this  differerce  is  not  greater  than 
three  times  the  probable  error,  the  mere  fact  that  it  is  greater  suggests  at 
least  a  tendency  for  Type  C  rooms  to  be  more  conducive  to  respiratory  illness 
than  those  of  Type  B. 

Minor  respiratory  illness  insufficient  to  cause  absence  amounts  to  a  rate 
of  43  in  Type  B  rooms  and  to  73  in  Type  C.  This  is  a  difference  of  30. 
The  greater  probable  error  is  9.0.  The  difference  is  thus  more  than  three 
times  the  probable  error  and  statistically  may  be  regarded  as  significant. 
Interpreted  in  other  words  the  system  of  fan  ventilation  representing  Type 
C  is  more  conducive  to  respiratory  illness  among  school  children  than  the 
window  ventilation  methods  of  Type  B. 

In  Chart  III  are  represented  graphically  the  absence  rates  as  well  as 
other  facts  pertinent  to  the  matter.  The  difference  in  average  temperature 
between  Type  A  and  B  rooms  was  4.8  degrees.  Relative  humidity  was  almost 
identical,  being  46  per  cent  in  the  A  rooms  and  45  in  B.  The  A  rooms  were 
judged  exceptionally  fresh  63  per  cent  of  the  time  as  against  31  per  cent 
for  B.  The  air  possessed  a  noticeable  odor  11  per  cent  of  the  time  in  A  and 
15  per  cent  in  B.  The  degree  of  congestion  was  the  same  in  both  types, 
namely:  11.5  square  feet  of  floor  space  per  pupil. 

In  the  second  comparison,  the  Type  B  rooms  averaged  67.0  degrees 
temperature  as  against  68.1  for  the  C  rooms,  a  difference  of  but  1.1  degrees. 
Relative  humidity  was  38  per  cent  in  B  and  40  per  cent  in  C.  The  B  rooms 
were  judged  exceptionally  fresh  18  per  cent  of  the  time,  the  C  rooms  22  per 
cent.  Odor  was  noticeable  17  per  cent  of  the  sessions  in  B  and  only  14  in  C. 


The  B  rooms  were  appreciably  more  congested,  the  square  feet  of  floor  spa< 
per  pupil  being  11.1  as  against  14.7  in  the  C  rooms. 

The  following  conclusions  appear  justified  from  the  evidence: 

1.  Kespiratory  sickness  is  no  greater  in  a  window  ventilated  schoolrooi 
kept  around  59  degrees  than  it  is  in  a  room  where  temperature  is  64. 

2.  Respiratory  sickness  is  greater  in  fan  ventilated  rooms,  such  as  are 
represented  in  this  study,  than  in  window  ventilated  rooms,  even  though  there 
is  not  more  than  a  degree  difference  in  temperature,  and  the  fan  rooms  are 
more  spacious. 

3.  It  is  low  temperature  rather  than  chemical  purity  of  the   air  which 
conveys  the  sensation  of  freshness. 

DISCUSSION  OF  VENTILATION  TYPES  REPRESENTED  IN  THIS  STUDY 

The  conclusions  arrived  at  in  discussing  the  relation  of  ventilation  to  colds 
raise  the  question  as  to  whether  all  methods  of  school  building  ventilation  by 
mechanical  means  are  discredited  by  this  test.  This  inference  is  of  course 
unwarranted.  The  results  of  this  study  apply  only  to  the  types  of  ventilation 
here  represented,  a  brief  description  of  which  will  be  given. 

The  selection  of  schools  was  made  by  the  writer  after  a  conference  with 
Mr.  Frank  G-.  McCann,  heating  and  ventilating  engineer  of  the  New  York 
City  Board  of  Education.  Altogether  over  fifty  schools  were  considered,  and 
more  than  half  of  this  number  were  visited  in  person  by  the  writer. 

There  were  many  factors  to  weigh  in  making  the  selection.  It  was  de- 
sired above  all  to  choose  schools  possessing  all  three  types  of  ventilation.  As 
previously  explained,  this  was  found  impossible  except  for  one  school.  These 
conditions  were  nearly  fulfilled  in  one  other  instance  wrhere  the  three  types 
were  found  in  two  schools  within  a  block  or  so  of  each  other.  For  conven- 
ience it  was  desirable  that  the  schools  should  be  located  within  Manhattan  and 
Bronx  Boros.  To  represent  this  territory,  selections  were  made  in  Lower 
Manhattan,  Central  Manhattan  and  Upper  Manhattan  and  the  Bronx.  It 
was  further  desired  that  the  ventilation  methods  should  have  already  been  in 
use  for  some  time  prior  to  the  experiment,  so  that  uniform  operating  condi- 
tions would  be  established.  It  was  possible  to  adhere  to  this  requirement  in  all 
but  one  school,  165,  in  the  first  study  and  all  but  four  in  the  second.  In 
these  four,  165,  97,  115  and  33  Bx.,  window  ventilation  was  arranged  by  block- 
ing off  the  fan  supply  inlets  to  the  rooms  and  by  installing  deflectors  at  the 
windows.  The  effort  was  made  to  select  schools  whose  mechanical  ventilation 
equipment  was  in  good  condition  and  in  capable  hands.  Lastly  it  was  essen- 
tial that  the  principal  of  the  school  should  be  in  sympathy  with  the  objects 
of  the  study. 

Schools  12,  147  and  22  were  located  in  lower  Manhattan,  the  first  on  Mad- 
ison and  Jackson  Streets;  the  second  on  Henry  and  Gouverneur,  and  the 
third  on  Stanton  and  Sheriff.  Schools  59  and  73  were  in  Central  Manhattan, 
the  former  on  57th  Street  near  Third  Avenue,  the  latter  on  46th  Street  near 

26 


Third  Avenue.  School  165  was  on  109th  Street  near  Broadway;  39  on  126th 
street  near  Second  Avenue ;  2  Bx.  on  169th  Street  near  Third  Avenue.  The 
schools  added  in  the  second  study  were  97  on  Mangin  Street  between  Stanton 
and  Houston,  in  the  lower  East  Side ;  115  on  176th  Street  near  Audobon  Avenue ; 
33  Bx.  on  184th  Street  and  Jerome  Avenue,  Bronx;  51  Bx.  on  Trinity  and 
Jackson  Avenues,  Bronx. 

The  date  of  erection  of  each  building,  as  well  as  the  type  of  building  ven- 
tilation is  shown  in  Table  XXII: 


TABLE  XXII 

SCHOOL 

DATE   OP   ERECTION 

AERATION                                     HEAT    CONTROL                              REMARKS 

AND  ADDITIONS 

12 

1908 

Window  and  Grav.  Exhaust 

Thermostatic 

147 

1898 

Plenum  Fan  and  Grav.  Exh. 

" 

22. 

1843-1873-1891-1902 

1  1          1  1      1  1        11         f  -t 

t  ^ 

73 

1880-1902 

Windows  and  Grav.  Exhaust 

Manual 

59 

1871-1904-1908 

Plenum  Fan  and  Grav.  Exh. 

Thermostatic        Also  air  washer 

165 

1898-1905 

<  <                   (  <           «               (  (                U 

it 

39 

1903 

Windows  and  Grav.  Exh. 

1  1 

2  Bx. 

1874-1886-1902 

Plenum  Fan  and  Grav.  Exh. 

11 

51  Bx. 

1915 

Plenum  and  Exhaust  Fans* 

ft                  Also  air  washer* 

33  Bx. 

1899 

Plenum  Fan  and  Grav.  Exh. 

<« 

115 

1914 

Plenum  Fan  and  Grav.  Exh. 

Also  humidifying  f; 

97 

1915 

<«                   (I            (I              4  i                ft 

"                  Also  air  washer 

*This  refers  only  to  the 

two  rooms  used  in  the  study. 

The  window  ventilated  rooms  had  direct  radiation  beneath  the  windows. 
In  the  first  study  there  were  no  deflectors  except  at  School  73.  In  the  second 
study  deflectors  were  provided  in  all  rooms  of  Type  A  and  B.  All  of  these 
rooms  had  gravity  exhaust  openings  to  permit  air  circulation.  It  is  best  that 
these  openings  be  in  the  inside  wall  opposite  the  windows.  This  arrangement 
did  not  exist  in  many  rooms,  the  openings  being  in  walls  adjacent  to  the 
windows  and  frequently  so  small  in  size  as  to  be  really  of  little  service  in  keep- 
ing the  room  well  aerated.  Direct  radiation  was  thermostatically  controlled 
in  all  cases  save  in  School  73,  where  it  was  manually  controlled. 

The  mechanical  ventilation  consisted  usually  of  plenum  fans,  air  being 
driven  into  the  classrooms  near  the  ceiling  and  leaving  through  gravity  exhaust 
openings  near  the  floor.  These  rooms  were  also  provided  with  direct  radia- 
tion under  thermostatic  control.  A  check  on  the  ventilation  was  had  by  means 
of  ribbons  on  the  inlet.  These  were  observed  by  the  nurses,  who  could  thus 
tell  in  a  rough  way  the  efficiency  of  the  blowers. 

The  system  at  School  147  gave  a  weak  and  irregular  air  flow  to  the  three 
classrooms  during  the  first  study,  and  windows  were  frequently  opened.  This 
condition  was  greatly  improved  in  the  second  study. 

School  22  had  a  plenum  fan  system  in  the  new  wing.  The  air  flow  in  the 
rooms  was  continuous  and  pronounced,  and  windows  were  rarely  opened. 
Anemometer  readings  at  the  register  face  made  on  January  8,  1917,  showed 
1640  cubic  feet  per  minute  in  Eoom  402,  1960  in  403  and  1620  in  Room  404. 

School  59  had  a  plenum  fan  system  in  the  new  addition  built  in  1908.  This 
consisted  of  two  blowers  and  an  air  washer.  This  equipment  was  in  most  capable 

27 


hands,  and  the  rooms  were  at  all  times  well  flushed  with  humidified  and  washed 
air.  Windows  were  always  kept  closed.  On  January  15,  1917,  anemometer 
measurements  showed  the  following  air  flow  in  cubic  feet  per  minute :  Room 
203—1400,  205—1300,  206—1740,  501—1150,  503—1380,  505—760.  During 
both  studies  there  was  continuous  and  pronounced  flow  in  all  rooms. 

School  165  had  a  plenum  fan  system  with  gravity  exhaust  which  proved 
inadequate  for  the  rooms  used  in  the  study.  At  times  air  flow  was  ample, 
again  deficient.  Conditions  were  better  in  the  second  study. 

School  2  Bx.  consisted  of  an  old  and  new  section,  the  latter  built  in  1902. 
This  section  contained  the  plenum  fan  ventilating  equipment  with  gravity  ex- 
haust. Air  flow  was  fairly  continuous  and  pronounced. 

The  orientation  of  the  classrooms  varied  somewhat  in  the  three  types, 
the  A  rooms  having  a  greater  amount  of  southern  exposure. 

TABLE  XXIII 
ORIENTATION  OF  CLASSROOMS  IN  FIRST  STUDY 


: 


VENTILATION 

N.,    N.E., 

w. 

S.,     S.    E., 

E. 

TYPE 

N.  W. 

s.  w. 

A 

5 

0 

12 

1 

B 

9 

3 

4 

5 

C 

9 

5 

3 

2 

RESULTS  IN  NEWER  SCHOOLS  ADDED  IN  SECOND  STUDY 

When  this  study  was  begun,  there  were  no  schools  erected  within  two  or 
three  years  which  could  be  used.  In  the  second  study  we  were  enabled  to 
add  four  schools,  three  of  which  had  just  been  opened  to  pupils  within  the 
year.  School  51  Bx.  contained  two  rooms  in  which  the  Ventilation  Commis- 
sion was  making  studies  on  the  effect  of  humidification,  both  being  ventilated 
by  plenum  and  exhaust  fans.  These  results  were  included  in  the  grand 
totals,  but  of  course  they  do  not  furnish  us  with  a  comparison  of  the  types 
forming  the  basis  of  this  study.  The  respiratory  sickness  rates  were  higher 
in  the  humidified  room.  Temperature  was  about  the  same  in  both.  Odor 
was  frequently  noticeable  in  the  humidified  room. 

TABLE  XXIV 
RESPIRATORY  ILLNESS  IN  SCHOOL  51 


VENTILATION 
TYPE 

ABSENCE 
RATE 

SICKNESS 
IN   AT- 
TENDANCE 
RATE 

TOTAL 
RESP. 
SICKNESS 
RATE 

TEMPERA- 
TURE 

RELATIVE 
HUMIDITY 

PER,  CENT 

SESSIONS 

ESP. 
FRESH 

ODOROUS 

Humidified 
Not  Humidified 

4.0 
14.7 

148. 
50. 

152. 

64.7 

67.6 

67.4 

44 

29 

0 
0 

39 
2 

School  33  was  an  older  building,  but  because  of  work  already  in  prog- 
ress there  by  the  Ventilation  Commission,  the  sickness  records  were  also  col- 
lected and  added  to  the  grand  totals  of  this  study.  Ventilation  was  by 

28 


means  of  plenum  fans  and  gravity  exhaust.  The  fan  inlets  were  blocked  off 
in  the  Type  B  rooms  and  deflectors  placed  at  the  windows.  The  respiratory 
sickness  rates  were  less  in  the  two  window  ventilated  rooms  than  in  the 
two  of  Type  C.  The  fan  rooms  were  slightly  warmer  but  less  odorous. 


TABLE  XXV 
RESPIRATORY  ILLNESS  IN  SCHOOL  33 


PER   CENT   SESSIONS 

VENTILATION 

ABSENCE 

SICKNESS 

TOTAL 

TEMPERA- 

RELATIVE 

ESP. 

ODOROUS 

TYPE 

RATE 

IN   AT- 

RESP. 

TURE 

HUMIDITY 

FRESH 

TENDANCE 

SICKNESS 

RATE 

RATE 

B 

C 

24.2 
37.0 

52 

72 

76.2 
109.0 

69.4 
70.6 

34 
30 

1 

2 

15 

3 

School  97  was  just  completed  in  1915  and  was  equipped  with  plenum 
fans  and  gravity  exhaust,  the  air  being  washed  and  humidified  before  entering 
the  rooms.  Three  rooms  were  chosen  to  represent  each  of  Type  B  and  C. 
The  respiratory  sickness  rates  were  the  lowest  here  of  all  the  schools.  Sickness 
was  less  in  the  fan  ventilated  rooms  than  in  the  window  rooms.  The  fan 
rooms  were  a  degree  warmer  and  were  much  better  aerated. 


TABLE  XXVI 
RESPIRATORY  ILLNESS  IN  SCHOOL  97 


PER  CENT  SESSIONS 

VENTILATION 

ABSENCE 

SICKNESS 

TOTAL 

TEMPERA- 

RELATIVE 

ESP. 

ODOROUS 

TYPE 

RATE 

IN  AT- 

RESP. 

TURE 

HUMIDITY 

FRESH 

TENDANCE 

SICKNESS 

RATE 

RATE 

B 

C 

5.6 
3.7 

47 

37 

52.6 

40.7 

66.7 
67.6 

42 

43 

49 

85 

32 
3 

The  location  of  this  school  was  along  the  East  River,  and  across  the 
street  was  a  large  stable  whose  odors  were  frequently  wafted  over  to  the 
school  at  times  of  east  wind.  This  interfered  with  the  free  use  of  the  windows. 
The  fan  ventilated  rooms  were  not  troubled  by  these  odors.  One  of  the  three 
window  rooms  was  on  an  enclosed  court  which  also  cut  down  free  air  circu- 
lation. The  experience  at  this  school  was  very  suggestive.  Here  was  an  il- 
lustration where  fan  ventilation  provided  a  more  satisfactory  result  than 
window  ventilation.  Schools  with  similar  locations  in  the  neighborhood  of 
noxious  odors  are  evidently  better  served  by  indirect  washed  air  than  by  tak- 
ing air  direct  from  the  windows.  The  teacher  of  one  window  room  was 
well  satisfied  and  much  preferred  it  to  the  fan  ventilation  of  the  building. 
The  majority  opinion,  however,  favored  the  fan  rooms. 

School  115,  erected  in  1914,  was  equipped  with  plenum  fans,  a  humidifying 
pan  and  gravity  exhaust  ducts.  Air  flow  was  at  all  times  ample.  Little  or 
no  use  was  made  of  the  humidifying  pan.  Respiratory  sickness  was  greater 
in  the  fan  ventilated  rooms. 


TABLE  XXVII 
KESPIRATORY  ILLNESS  AT  SCHOOL  115 


PER  CENT  SESSIONS 

VENTILATION 
TYPE 

ABSENCE 
RATE 

TEMPERATURE 

RELATIVE 
HUMIDITY 

ESP. 
FRESH 

ODOROUS 

B 

C 

30.4 

47.2 

67.6 
67.6 

28. 
26. 

2 
1 

3 
6 

(Note:     The  comparative  data  on  sickness  among  pupils  in  School  are  not  available  for 
this  school.) 

A  great  deal  of  dissatisfaction  with  the  fan  ventilation  existed  among 
the  teachers  in  this  school.  Complaints  of  dryness  and  drafts  were  common. 
The  window  rooms  were  by  far  the  more  comfortable. 

In  the  three  schools  added  in  the  second  study,  where  Types  B  and  C  were 
studied,  the  window  rooms  showed  less  respiratory  illness  in  two,  and  more 
in  one.  This  supports  the  findings  in  the  other  schools. 

In  view  of  the  favorable  showing  for  fan  ventilation  in  a  very  modern 
school  with  humidification  such  as  97,  it  may  appear  that  the  results  of  this 
study  do  not  apply  to  installations  of  the  latest  design.  It  is  true  that  we 
cannot  generalize  too  widely  in  the  matter,  but  on  the  other  hand,  School  59 
possessed  very  modern  equipment  and  was  operated  in  every  way  as  per- 
fectly as  97,  and  yet  the  sickness  rates  here  were  higher  than  in  the  other  rooms 
crudely  equipped  for  window  ventilation. 

The  buildings  used  were  representative  of  what  existed  in  New  York  City 
at  the  time.  All  were  not  of  the  very  latest  construction;  nor  were  all  of 
ancient  pattern  and  design.  All  types  were  represented.  The  buildings 
were  equipped  and  built  with  plenum  fan  ventilating  systems.  These  systems 
were  not  ideal.  They  possessed  faults  as  judged  from  the  ventilating  engi- 
neer's viewpoint  of  the  year  1915. 

The  rooms  fitted  up  for  window  ventilation  were  not  built  for  this  pur- 
pose. They  were  altered  for  the  plan  in  mind.  In  no  instance  were  the  fa- 
cilities complete. 

As  a  comparison  of  average  fan  ventilation  in  New  York  City  school  build- 
ings and  ventilation  of  the  same  buildings  without  fans,  the  present  study 
is  entirely  fair.  If  either  type  of  room  is  lacking  in  its  equipment,  it  is  the 
window  ventilated  rooms  which  labored  under  the  greater  handicap. 

METHODS  OF  RECORD  TAKING 

A  word  may  be  devoted  here  to  the  method  of  collecting  records. 

Each  classroom  was  visited  morning  and  afternoon.  In  the  morning  a 
record  was  made  of  the  pupils  absent  and  of  the  pupils  in  attendance  who 
exhibited  signs  of  a  cold.  The  cause  of  absence  was  ascertained  by  a  visit  to 
the  home.  If  a  physician  were  in  attendance  his  diagnosis  was  accepted.  If 
110  physician  were  in  attendance,  the  nurse  diagnosed  the  case,  and  when  in 
doubt,  her  opinion  was  checked  by  a  medical  inspector.  Many  absences  were 
not  due  to  illness,  as  the  subsequent  records  will  indicate. 

The  diagnosis  of  minor  illness  among  pupils  in  school  was  made  by  the 

30 


nurse.  Many  pupils  with  symptoms  of  a  cold  were  pointed  out  to  the  nurse 
by  the  teachers. 

At  the  beginning  of  the  afternoon  session  the  nurse  again  visited  each 
room  to  ascertain  absences,  and  the  causes  were  determined  in  the  usual  man- 
ner. No  effort  was  made  at  this  time  to  determine  illnesses  among  those  pres- 
ent. A  child  recorded  as  having  coryza  in  the  morning  was  credited  with 
the  same  affection  in  the  afternoon  if  he  or  she  were  present  in  school. 

In  addition  to  the  routine  described  above,  the  nurse  entered  each  class- 
room at  about  10:30  A.M.  and  2:15  P.M.,  or  just  prior  to  the  midsession 
aeration  of  the  room,  and  recorded  her  impressions  of  the  air  conditions  and 
made  determinations  of  temperature  and  humidity  with  a  sling  psychrometer. 
The  actual  procedure  was  to  enter  the  room,  walk  down  the  side  aisle  to  the 
rear  and  thence  up  the  middle  aisle  to  the  center  of  the  room.  The  impres- 
sion of  odor  was  then  recorded  in  terms  of  the  scale  given  below.  Next 
in  order  were  recorded  the  sensations  of  temperature,  moisture  and  air  motion 
in  terms  as  shown.  The  psychrometer  was  then  swung  at  a  level  of  about 
three  to  four  feet  from  the  floor,  the  wet  bulb  having  been  moistened  from  a 
small  bottle  of  water  carried  for  the  purpose,  and  both  wet  and  dry  bulb 
readings  noted. 

VOTING  SCALES  OF  SENSE  IMPRESSIONS 
ODOR  TEMPERATURE  MOISTURE  AIR  MOTION 


Exceptionally 

fresh 

1 

Too  warm 

40 

Moist 

B 

Dead 

R 

Odor  absent 

2 

Satisfactory 

30 

Neutral 

C 

Bet.  R  &  T. 

S 

• 

Breezy  or 

Odor 

3 

Cool 

20 

Dry 

D 

drafty 

T 

Before  departing,  the  nurse  made  notations  of  the  position  of  windows, 
whether  open  or  closed,  position  of  door  and  transom  and  activity  of  flag  at- 
tached to  the  inlet  register  in  the  fan  ventilated  rooms. 

Prior  to  the  beginning  of  the  study  the  nurses  were  carefully  rehearsed 
in  their  duties  and  were  given  demonstrations  in  the  use  of  the  sling  psy- 
chrometer. 

The  diagnosing  of  respiratory  illness  was  frequently  checked  up  by 
medical  school  inspectors  and  the  supervising  physician  of  the  study,  Dr.  Leo- 
pold Marcus. 

For  several  weeks  during  the  second  study  all  diagnoses  were  made  by 
medical  inspectors.  Their  opinions  fully  confirmed  the  interpretations  made 
by  the  nurses  and  verified  the  casual  inspections  of  physicians  made  prior  to 
this  time. 

Respiratory  illness  is  responsible  for  19  per  cent  of  absences  from  school ; 
illness  other  than  respiratory  (including,  however,  the  acute  contagious  dis- 
eases) 37  per  cent ;  and  causes  other  than  illness  44  per  cent. 

THE  SCHOOL  PERSONNEL  AND   RESPIRATORY   ILLNESS 

The  personnel  of  the  pupils  is  a  marked  factor  in  determining  the  respira- 
tory illness  rates  distinct  from  environmental  influences.  This  was  recognized 
at  the  outset,  and  an  attempt,  but  partially  successful,  was  made  to  equalize 

31 


this  influence  among  the  three  ventilation  types.     Some  schools  were  high  in 
respiratory  illness  in  both  studies,  while  others  were  low  in  both. 

Considering  the  total  respiratory  illness  rates  for  both  studies,  Schools 
12  and  147  had  the  lowest  figures.  These  schools  are  on  the  lower  East  Side 
in  the  heart  of  the  Russian-Jewish  districts.  The  buildings  are  old.  The 
average  temperature  was  around  64  degrees.  These  two  schools  may  be 
contrasted  with  Schools  165  and  115,  which  were  located  in  very  good  neigh- 
borhoods and  were  attended  by  native  "born  children  of  well-to-do  parents. 
Both  are  of  more  recent  construction  than  12  and  147,  P.  S.  115  having  been 
erected  in  1914.  In  spite  of  environmental  and  social  advantages,  the  upper 
Manhattan  schools  had  high  rates  from  respiratory  illness. 

In  general,  the  schools  located  in  congested  districts  and  attended  by 
pupils  of  inferior  economic  and  sanitary  status  had  less  illness  than  those 
located  in  the  better  class  neighborhoods. 

Averaging  the  rates  by  social  and  economic  status,  the  above  facts  stand 
out  clearly. 

RESPIRATORY    ILLNESS    RATES 

SOCIAL    AND  AMONG   THOSE 

ECONOMIC     STATUS  SCHOOLS  ABSENT  IN    ATTENDANCE 


Very  good                                          165,  115,  33  34.7  78 

Good  59,  2  Ex.,  51  Bx.  10.6  85 

Poor  12,  147,  22,  97,  73  7.6  35.4 

Very  Poor                                                    39  10.8  21.6 

An  explanation  of  this  unexpected  result  is  not  easy  to  give.  It  prompts 
the  query — Does  prosperity  undermine  health  and  are  our  children  of  supe- 
rior social  status  coddled  to  their  detriment? 

It  is  entirely  possible  that  the  children  in  the  poorer  districts  acquire  a 
more  specific  immunity  by  reason  of  their  congested  manner  of  living.  It 
has  been  shown  by  Vaughan  and  the  writer  that  the  city  boy  made  a  hardier 
soldier  in  our  army  camps  in  1917  and  1918  and  was  less  subject  to  disease 
than  the  country  boy.* 

It  is  also  possible  that  the  pupils  in  the  poorer  neighborhoods  become 
"hardened"  by  slight  exposure  to  cold,  the  body  becoming  less  sensitive 
to  environmental  changes.  Overheating  and  overeating  are  drawbacks  to 
which  this  class  is  less  familiar  than  their  more  fortunate  schoolmates.  In 
many  respects  material  success  converts  a  man  into  a  less  perfect  physiologic 
machine.  As  the  battle  with  the  elements  becomes  less  severe,  the  stimula- 
tion to  physiological  combativeness  wanes.  Lack  of  exercise,  complex  food 
as  distinguished  from  simple  coarse  food,  and  life  in  uniformly  and  highly 
heated  buildings  without  question  weakens  the  body  physically.  In  these 
statements  may  be  found  the  explanation  of  this  peculiar  distribution  of  the 
ordinary  forms  of  respiratory  illness. 

In  view  of  the  fact  that  the  Type  C  rooms  had  more  girls  than  the  others, 
the  question  arises  as  to  whether  this  would  not  account  for  the  greater  ill- 


*"Communicable  Disease  in  the  National  Guard  and  National  Army  of  the  United  States  During 
the  Six  Months  from  September  29,  1917,  to  March  29,  1918."  By  Col.  V.  C.  Vaughan  and  Capt.  T. 
G.  T.  Palmer,  Jour,  of  Laboratory  and  Clinical  Medicine,  Vol.  Ill,  No.  II,  August,  1918.  Pages  693-693. 

32 


ness.**  This  presupposes  that  girls  are  more  susceptible  to  colds  than  boys, 
a  supposition  for  which  there  is  no  justification  so  far  as  we  know.  There  is 
no  indication  of  this  in  the  present  study. 

In  the  first  study,  P.  S.  165,  Type  C  had  the  highest  respiratory  absence 
rate,  yet  only  28%  of  the  pupils  were  girls.  The  next  highest  rate  was  at  P. 
S.  2,  Bronx,  Type  B,  where  50%  of  the  pupils  were  girls.  The  third  highest 
rate  was  at  P.  S.  165,  Type  B,  where  all  the  pupils  were  boys. 

P.  S.  2,  Bronx,  Type  C,  had  high  illness  rates  in  the  second  study  and  yet 
only  one-third  of  the  pupils  were  girls. 

P.  S.  12  and  147  had  low  rates  in  both  studies  and  the  ratio  of  girls 
to  boys  was  four  to  one  in  the  first  study  and  three  to  one  in  the  second. 

TYPES  OF  RESPIRATORY  ILLNESS 

Lacking  the  diagnosis  of  a  medical  man  as  to  the  specific  type  of  respira- 
tory illness  in  all  instances  of  this  study,  we  cannot  publish  these  facts  with 
any  degree  of  certainty.  However,  we  submit  the  statements  of  the  nurses, 
which  it  will  be  remembered  were  frequently  checked  by  the  medical  school 
inspectors. 

The  most  prevalent  form  of  respiratory  illness  causing  absence  was  ton- 
sillitis, which  amounted  to  32  per  cent  of  the  total.  Slightly  less  prevalent 
were  coryza  (25%)  and  bronchitis  (22%).  Laryngitis  and  pharyngitis  were 
less  frequently  mentioned. 

Of  the  illnesses  among  those  present  in  school,  coryza  representing  62%  of 
the  total,  is  the  most  prominent.  Bronchitis  stands  second  with  20%  and 
laryngitis  third  with  10%. 

Tonsillitis  is  especially  prevalent  in  the  Type  C  rooms.  Other  affections 
are  greater  in  Type  C,  but  no  one  affection  seems  to  be  characteristic  of  any 
ventilation  type. 

Illness  other  than  those  listed  under  the  term  (e respiratory  illness"  were 
due  to  a  great  many  causes.  Diphtheria,  scarlet  fever,  measles  and  chicken- 
pox  were  responsible  for  a  small  amount  of  absence,  but  absence  from  these 
causes  combined  amounts  to  less  than  that  due  to  tonsillitis  alone.  In  the 
first  study  the  indefinite  term  "sickness"  was  given  as  responsible  for  more 
absence  than  any  single  cause.  More  specific  terms  were  used  in  the  second 
study.  Headache  was  a  frequent  cause  of  absence,  being  mentioned  most 
frequently  in  the  Type  C  rooms.  Appendicitis  was  responsible  for  a  number 
of  absences.  A  miscellaneous  group  of  innumerable  causes  makes  up  the 
bulk  of  the  absence  causes.  No  particular  form  of  illness  seems  to  charac- 
terize any  ventilation  type. 

WEATHER    AND    RESPIRATORY    ILLNESS 

Although  aside  from  the  ventilation  question  it  is  of  interest  to  note  the 
fluctuations  in  respiratory  illness  from  week  to  week  and  the  corresponding 
changes  in  weather.  From  the  preceding  pages  it  is  evident  that  the  indoor 

**The  percentage  of  girls  in  Type  C  was  60  in  the  first  study  and  54  per  cent  in  the  second. 
The  figures  for  Type  B  were  37  and  31  and  for  A,  41  and  49. 

33 


atmosphere  has  an  influence  on  health.    By  combining  the  records  of  all  schools 
it  will  be  possible  to  follow  the  seasonal  change  in  respiratory  illness. 

In  Chart  IV  we  have  shown  the  sickness  rate  in  each  type  of  ventilation 
by  weeks  along  with  the  room  temperature  and  relative  humidity.  The  data 
for  Schools  97,  115  and  51  Bx.  are  omitted,  as  records  were  available  only 


150 
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FIRST    STUDY 
FE.B.  14  -  APR.lSjgik, 

SECOND    STUDY 

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t  ACept   97,  115,   31  Bx                                                                   ^ 
A-  Cold,  wi-  Jo*   venti  at«d  rooms      (about     5»  •) 
B-  Cool,    window    vent,lat«d  room*       (about     65*) 
C-  fan-  ventilated    room*                            (about     69'} 

Chart  IV. 

during  the  last  seven  weeks  of  the  second  study.  The  fan  ventilation  group 
shows  the  greatest  amount,  and  the  window  ventilated,  moderate  temperature, 
the  lowest  amount  of  respiratory  illness  throughout. 

Respiratory  illness  declines  from  February  to  April  although  the  fan  ven- 
tilated rooms  show  the  highest  point  during  the  middle  of  March.     Colds 


34 


are  at  a  higher  level  in  October  than  they  are  in  April.  In  the  Type  C  and 
B  rooms  colds  increase  abruptly  during  the  first  5  weeks  in  the  Autumn. 
Type  C  then  holds  this  level.  The  B  rooms  fall  off  and  do  not  rise  again  until 
January.  Colds  in  the  Type  A  rooms  increase  gradually  from  October  till 


RESPIRATORY    ILLNESS  AMONG-    SCHOOL  CHILDREN 
AND     IT'S    ASSOCIATION    WITH    THE.    WEATHE.R 
By  Weeks 

FIRST     STUDY                                              StCOND    STUDY 
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Chart  V. 

the  first  week  in  December.    From  this  point  they  decline  only  to  rise  again 
the  latter  part  of  January. 

Room  temperature  in  the  fan  ventilated  rooms  is  the  most  uniform,  keep- 
ing quite  constantly  between  68  and  69  degrees.  In  the  window  rooms  Type 
B,  temperature  has  a  slightly  wider  variation,  from  65  to  68  degrees,  but  is 
consistently  below  Type  C.  In  Type  A  rooms  we  note  a  wide  variation, 


35 


from  55  to  66.  During  February  and  March  these  rooms  run  between  50 
and  60,  and  this  is  true  also  in  December  and  January.  In  April  and  Novem- 
ber the  temperature  is  from  60  to  65. 

Kelative  humidity  is  greatest  in  the  A  rooms.  It  is  lowest  in  March  and 
January.  As  will  be  seen  from  a  later  chart,  humidity  is  influenced  mostly 
by  outdoor  temperature  and  next  to  that  by  outdoor  moisture. 


Total 

Respiratory 
S/ckness 
Pate. 
Weather 

Corn  fort 

Vote. 


8 


RESPIRATORY  ILLNESS,  WEATHER  AND  THE 
SENSATION  OF  WEATHER 


Mean  Outdoor 
Temperature 


Total  Deheating 
Potver  <*^ 
\Heather~ 


The  general  points  to  be  noted  from  this  chart  are  that  colds  are  more  common 
in  fall  than  in  late  winter,  that  even  though  the  room  temperature  and  humid- 
ity in  Types  B  and  C  are  quite  similar,  there  is  an  appreciable  difference  in 
the  prevalence  of  colds,  and  finally  that  the  course  of  respiratory  illness  from 
week  to  week  is  guided  mainly  by  influences  other  than  the  temperature  and 
humidity  of  the  classroom. 


36 


That  outdoor  weather  bears  a  close  relationship  to  colds  is  illustrated 
by  the  various  graphs  on  Chart  V.  Far  overshadowing  other  weather  in- 
fluences is  temperature.  In  the  spring,  colds  decrease  as  the  weather  becomes 
warmer.  In  the  fall,  oncoming  cold  weather  is  coincident  with  increasing 
respiratory  affections. 


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THE    SEQUENCE  OF  COLDS   AND  PNEUMONIA 

JAN. 

NEW  YORK    CITY    1916-1917 

Colds    among  3000  school   children  expressed 
as  a  rate    per  1000   pupil    session    registration 
units. 
Total    deaths    from    pneumonia  (all  forms) 
in    New  York   City. 

Chart   VII. 

What  is  understood  as  changeable  weather  does  not  have  marked  influence 
on  colds.  The  third  week  in  February  shows  an  extreme  daily  change  in 
temperature  with  no  accompanying  increase  in  colds. 

Relative  humidity  shows  wide  variations  from  week  to  week  without  corre- 


37 


spending  undulations  in  the  sickness  curve.  The  late  winter  is  more  blus- 
tery than  the  fall,  and  yet  colds  are  less  numerous  in  the  windy  season. 

Temperature  and  colds  are  most  closely  related.  Is  it  temperature  per 
se  or  the  total  chilling  effect  of  all  weather  elements  combined?  The  formula 
derived  by  Dr.  Leonard  Hill  of  England  from  his  instrument  known  as  the 
kata-thermometer  permits  us  to  sum  up  in  a  single  expression  the  combined 
deheating  effect  of  cold,  evaporation  and  wind  action.*  From  the  mean 
daily  outdoor  temperature,  vapor  pressure  and  wind  velocity  we  have  com- 
puted the  mean  "  total  H"  or  total  deheating  power  of  the  elements.  This 
graph  has  been  placed  alongside  curves  for  respiratory  illniess  in  the 
second  study,  and  mean  temperature  and  a  fourth  curve  labelled  " comfort." 
The  comfort  vote  is  a  summary  of  the  recorded  daily  impressions  of  the  tem- 
perature feeling  of  the  weather,  as  judged  by  three  members  of  the  staff 
of  the  Ventilation  Commission. 

The  kata  and  temperature  curves  closely  parallel  each  other.  In  some 
respects  the  kata  curve  is  more  closely  associated  with  the  rise  and  fall  of 
illness  than  the  temperature  curve.  Thus,  the  kata  curve  shows  increasing 
cold  for  the  first  four  weeks  corresponding  to  increasing  illness.  The  tem- 
perature curve  shows  no  increase  in  cold  in  the  fourth  week  over  the  third. 

Illness  falls  off  as  the  temperature  stabilizes.  In  the  7th  week  tempera- 
ture again  descends,  and  sickness  picks  up.  The  10th  week  is  much  colder  as 
judged  by  the  kata  reading  although  the  temperature  is  no  lower.  There  is 
however,  very  low  humidity  and  high  wind  velocity,  which  are  heat  extrac- 
tors. These  data  suggest  that  it  is  the  total  chilling  effect  of  the  atmosphere 
rather  than  low  temperature  alone  that  is  conducive  to  illness. 

The  curve  of  outdoor  temperature  comfort  closely  parallels  the  temperature 
curve,  more  so  than  the  kata  curve. 

The  sequence  of  mild  colds  in  November,  followed  by  heavier  colds  in 
December  and  then  by  pneumonia  in  midwinter,  is  strongly  suggestive  of  a 
progressive  weakening  of  vitality.  Our  mid-winter  pneumonia  peak  is  thus 
the  result  of  attrition  of  vital  resistance  caused,  among  other  things,  by  acute 
respiratory  affections  in  the  months  preceding. 

SUMMARY  AND   CONCLUSIONS 

Prom  the  results  of  this  study  there  appears  to  be  something  inherent  in 
the  indirect  method  of  ventilating  schoolrooms  by  means  of  forced  draught  and 
gravity  exhaust,  as  practiced  in  this  study,  that  is  productive  of  respiratory 
affections,  something  which  is  not  present  in  rooms  ventilated  with  windows 
and  gravity  exhaust.  What  these  unfavorable  elements  are  is  not  entirely 
clear.  Higher  temperature  is  one.  Uniformity  of  temperature  and  air  flow 
is  another.  Uniformity  is  characteristic  of  the  fan  ventilated  room.  In  an 
unvarying  atmosphere  the  occupants  miss  that  pleasant  stimulating  effect. 
Evidently  the  absence  of  this  quality  affects  health  adversely  as  well  as 
comfort. 


*"The  Measurement  of  the  Rate  of  Heat  loss  at  Body  Temperature  by  Convection,  Radiation 
and  Evaporation."  By  Leonard  Hill,  F.  R.  S.,  O.  W.  Griffith  and  Martin  Flack,  Philosophical  Trans- 
actions of  the  Royal  Society  of  London.  Series  B.  Vol.  207,  pgs.  183-220.  1916. 

38 


The  temperature  of  window  ventilated  schoolrooms  may  be  reduced  as  low 
as  59  degrees  without  increasing  the  prevalence  of  colds. 

It  must  not  be  inferred  that  window  ventilation-  as  represented  in  this 
study  was  uniformly  satisfactory.  It  was  not.  As  a  rule  the  rooms  exposed 
on  the  east  do  not  fare  as  well  as  others.  Ample  exhaust  openings  are 
better  than  those  of  small  area.  There  is  the  matter  of  location  of  outlets 
with  respect  to  the  windows,  location,  size  and  control  of  direct  radiation, 
window  deflectors,  etc.,  which  affect  the  success  of  window  ventilation.  All 
of  these  factors  must  be  studied. 

In  spite  of  our  inadequate  knowledge  of  window  ventilation  at  its  best, 
the  fact  remains  that  the  window  rooms  of  this  study,  even  though  of  crude 
arrangement  and  not  built  originally  for  the  purpose,  competed  on  favorable 
terms,  from  a  hygienic  and  aesthetic  standpoint,  with  the  most  elaborate 
and  costly  fan  and  duct  equipment.  The  tendency  in  the  past  twenty  years 
has  been  away  from  natural  and  toward  mechanical  ventilation.  The  time 
and  effort  of  the  heating  and  ventilating  engineer  has  been  directed  toward 
the  perfecting  of  mechanical  means  for  aerating  buildings.  What  would 
the  same  amount  of  effort  have  yielded  if  expended  on  the  development  of 
natural  ventilation?  Possibly  something  of  great  value  and  at  less  expense. 

Because  window  ventilation  is  practicable  for  the  ordinary  schoolroom, 
it  does  not  follow  that  the  assembly  room,  the  theatre  and  other  places 
seating  several  hundred  people  can  also  be  dealt  with  in  this  manner.  Each 
type  of  enclosure  must  be  handled  as  a  distinct  problem.  Natural  ventilation 
has  its  limitations.  That  the  schoolroom  is  not  beyond  these  limitations  is 
the  indication  of  this  study. 

The  factors  which,  above  all  others,  promote  comfort,  health  and  effi- 
ciency are  coolness  and  fluctuating  air  motion.  If  the  teacher  maintains  her 
classroom  in  a  changing  condition,  without  draughts,  between  64  and  70 
degrees,  with  the  mean  lying  nearer  the  lower  figure,  it  matters  little  from 
a  practical  standpoint  what  the  other  measurements  of  ventilation  indicate. 
To  this  standard  the  room  properly  equipped  with  window  ventilation  and 
gravity  exhaust,  can  readily  conform. 

In  its  quantitative  effect  on  respiratory  illness  school  ventilation  is  of 
much  less  moment  than  the  outdoor  weather  influence.  Respiratory  affections 
increase  with  the  onset  of  cold  weather.  They  diminish  with  the  advent  of 
mild  weather  in  the  spring.  Wind  and  humidity  accentuate  the  temperature  in- 
fluence. Sunlight  exerts  at  least  a  warming  influence  sufficient  to  modify 
the  unfavorable  effect  of  cold.  Abrupt  changes  in  temperature  do  not  in- 
fluence respiratory  illness  as  much  as  one  might  expect  from  everyday 
experience. 

The  sanitarian  is  interested  in  the  prevention  of  the  tremendous  increase 
in  the  mortality  from  the  pneumonias,  which  occurs  in  cold  weather.  If  it 
is  possible  to  mitigate  the  unfavorable  weather  effect  by  the  proper  regulation 
of  the  indoor  atmosphere,  it  behooves  the  public  health  fr&ternity  to  bend 
every  effort  toward  this  goal.  The  problem  is  an  alluring  one.  The  results 
of  this  school  study  hold  forth  much  promise  in  this  direction. 

39 


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